Walter Ebeling

Chapter 9, part 2
Pests Attacking Man and His Pets

Part 1 | Part 3 | Part 4


In this section, wasps of varying degrees of importance because of their stings will be discussed. They are contained in 4 superfamilies. Best known is the superfamily Vespoidea, which includes the social wasps (yellowjackets, hornets, umbrella wasps, and the genus Mischocyttarus), all in the family Vespidae. The vespids construct a nest of paperlike material, consisting of wood, foliage, or cellulosic debris, chewed up and elaborated by the insects. The nests may be of various sizes, and may be constructed above or below ground, depending on the species. The family Vespidae also includes species of solitary wasps in the subfamilies Masarinae and Eumeninae. The superfamilies Sphecoidea, Bethyloidea, and Scolioidea contain only solitary wasps.


Millions of people are stung by venomous arthropods each year, and many thousands of these are seriously envenomated. Social wasps are only slightly less incriminated than bees in the number of fatalities for which they are responsible, and each of these 2 groups is more important than spiders, scorpions, and ants combined in this respect. Besides the approximately 22 deaths per year recorded as being directly caused by bees and wasps, there is no way of knowing how many other deaths reported to be caused by "heart attacks" and "heat strokes" may actually have resulted from the sting of a venomous insect (Parrish, 1959, 1963), or how many deaths attributed to "automobile accidents" may have resulted when bees or wasps caused the accidents, either by their stings or by the consternation and loss of vehicle control resulting from their mere presence (Miller, 1956).

Some social wasps, particularly yellowjackets, are greatly benefited by association with man, for in his garbage cans, discarded food materials, and trasli and garbage dumpsites he offers much greater sustenance to scavenging species than they can find in nature. Predatory species are attracted to flies that abound in such areas. Therefore, in wilderness regions, wasps are often abundant around human habitations and camps, but are rarely seen elsewhere. The relative importance of wasps in relation to other venomous arthropods will probably increaae with the growth of human population, and particularly with the increase in the.number of parks, camps, recreation areas, and suburban developments in formerly uninhabited places. Wasps decrease the desirability of recreation areas for public use.

In most of the country, wasps vary greatly in abundance from year to year. The number found in late summer depends to some extent on the weather during the preceding spring. If an early spring prompts queens to establish their nests and the weather then becomes inclement for a prolonged period, the wasp population can be greatly diminished (Andrewes, 1969). In California, the wasp population is far less variable from year to year than it is in parts of the country with more severe changes in spring weather.

Description. The vespid wasps are medium sized, and usually black and yellow in color. Species of the most common genus, Vespula, are readily distinguished by the jagged bands of black and bright yellow on the abdomen (plate VII, 3, 4; figure 226, figure 227). The wings are folded longitudinally. The antennae are elbowed, but not so abruptly as in ants, and the scape (basal segment) is long. The mouthparts are of the "chewing-lapping" type (figure 049, chapter 4). The middle tibiae have 2 apical spurs and the claws are simple. Generally there are 3 castes: the queen, a mated female that has hibernated over the winter before starting the nest; the males, produced only in the late summer or fall from unfertilized eggs; and the workers, infertile females. In Vespula, the queen is usually about 25%, longer than the workers, whereas in Polistes and Mischocyttarus, queens, males, and workers are about the same size.

Biology. The queen overwinters under loose bark, in cracks andcrevices, and occasionally in attics or similar sheltered locations.In the spring, she builds a few "paper" cells in a suitable location and lays a single egg in each cell. She feeds the legless, white larvae on meat or other proteinaceous food fragments, which she first macerates with her mandibles. These larvae become workers, and take over all the duties of the community, such as nest enlargement, providing food, and feeding the continuous broods of larvae. Throughout the summer the nest is enlarged, and the wasp population increases to a maximum that ranges from about 200 in the nests of Polistes and Mischocyttarus at any one time, to as many as 15,000 individuals in the nests of Vespula (Bohart and Bechtel, 1957). There are great differences in the numbers attained by different species, and even within a species nests vary greatly in size. Mature Vespula pensylvanica nests in southern California appear to have an average of about 3,000 individuals. Mature nests of the most common species of Polistes (P. fuscatus and P. apachus) generally have from 20 to 30 individuals, and the largest one found by R. E. Wagner (personal communication), a nest of P. f. aurifer, had 72 individuals.

Nests decline in summer or fall, and males and new queens are produced. The new queens of many species (most Vespula) are reared in specially constructed cells that are much larger than those in which the workers and males develop. The new males and queens leave the nest, and after mating the queens go into hibernation until the next spring. The nests of social wasps are used for only 1 year.

The adult social wasps feed on nectar, honeydew, fruit juices, sap, or similar substances. The proteinaceous food for the larvae consists of other insects and spiders if the wasps are predators, or bits of meat from any source if they are scavengers. After the workers take over the work of feeding the larvae, they continue to do so during their entire larval development. While the worker is feeding the larva, the larva exudes a drop of trophallactic fluid from its mouthparts. This fluid is ingested by the worker and provides its required proteins. Queens feed on nectar in the spring, and the workers and males feed on it in the fall, when there are no more larvae in the nest. Apparently the new queens, after mating, rapidly seek overwintering quarters, for they are not seen feeding. (R.E. Wagner, personal communication).

The Stinger of the Wasp

The stinging apparatus of the wasp is not fundamentally different from that of the honey bee (see figure 264, later in this chapter), but the stinger is larger and is semicylindrical in shape. The wasp can easily withdraw its stinger from human flesh to reinsert it or to escape, because the lancets of most wasp stingers, unlike those of the bee, are not barbed. Envenomation from the stings of hymenopterous insects is discussed under the heading "Hymenopterism" later in this chapter. Social wasps are more hazardous to humans than solitary wasps, not only because of their greater abundance but because the victim may be stung by many wasps at one time if he happens to disturb their nest (Fluno, 1961).


This is the subfamily that contains the typical yellowjackets, so called because of the black-and yellow pattern of the majority of species, although in some species a very pale yellow or "white" is substituted for the deeper yellow. In the Vespula species, the ground color of the integument is black. The yellow (or white) is present in a series of maculations that are quite variable but nevertheless present a distinct pattern, most strikingly exhibited on the abdomen. Therefore, the color pattern of the abdomen is the character most easily used to distinguish species. ln figure 226, the typical abdominal color patterns are shown for 6 Vespula species found only in the West (V. pensy!vanica, V. atropilosa, and V. sulphurea) or widely distributed throughout the North American continent, including the western states (V. vulgaris, V. arenaria and V. maculate). In figure 227, the patterns are shown for the most important species confined to the East.

The facial morphology (figure 228) provides the taxonomic character that distinguishes the 2 subgenera. In the subgenus Vespula, the oculomalar distance (distance between the eyes and mandibles) is always less than half the length of the penultimate (next to last) antennal segment. In the subgenus Dolichovespula, the oculo-malar distance is greater than half, and is usually as long as or longer than the penultimate antennal segment. The subgenus Dolichovespula is represented by V. arenaria and V. maculata in figure 226.

A key to the Vespula species of the Pacific Coast states was prepared by Bohart and Bechtel (1957). The accompanying practical field key for all presently known North American Vespula species was prepared by the author's co-workers, R. E. Wagner and D. A. Reierson. When using this key, it is important to examine as many specimens as possible because atypical individuals sometimes exist which can only be correctly determined by using secondary characters not specified in the key.


  1. Top and sides of head brownish .......Vespa crabro germana
    Top and side of head black, marked with yellow or white (genus Vespula).... 2

  2. Eyes nearly touching the upper edge of the jaws (figure 228)........(subgenus Vespula) .... 3
    Eyes separated from the upper edge of the jaws (subgenus Dolichovespula) ... 13

  3. Top of thorax with 2 prominent longitudinal yellow stripes ....... 4
    Top of thorax without such stripes.......... 5

  4. Undersurface of abdomen bright yellow. ........ V. sulphurea
    Undersurface of abdomen conspicuously marked with black..................... V. squamosa

  5. Pale markings whitish..................... 6
    Pale markings yellow...................... 7

  6. Reddish markings present on sides of abdomen.....................V. intermedia
    Abdomen without reddish markings..................V. consobrina

  7. Eyes encircled with yellow........ V. pensylvanica
    Eyes with some black contacting them at top ...... 8

  8. Long basal segment (scape) of antennae black, or with only a short yellow marking near its center................................. 9
    Scape black with yellow marking for most of its length................................. 11

  9. Yellow stripe behind eyes, usually with dark or cloudy marking on it; clypeus with a prominent vertical black bar............V. vulgaris.
    Stripe behind eyes entirely yellow........... 10

  10. Black spots present on top of at least I abdom inal tergite or on the second abdominal sternite ...... V. germanica.
    Black spots not present as above..........V. maculifrons

  11. Markings on second abdominal tergite variable, ranging from predominantly yellow, with a prominent central black marking accompanied by a pair of lateral black spots, to predominantly black, with the posterior yellow band similar in width to those on the succeeding segments ... 12
    Markings on second abdominal tergite predominantly black, with a yellow posterior band much narrower than those on tergites 3 through 5; free black spots usually present on tergites 4 and 5.................... V. vidua

  12. Clypeus with 3 black spots or rarely an anchor shaped marking; stripe behind eyes entirely yellow or with a small black interruption near its center; second abdominal sternite with free black spots .... V. atropilosa
    Clypeus with a longitudinal central black bar; stripe behind eyes broadly interrupted by black. Second abdominal sternite rarely with free black spots.................. V. acadica

  13. Pale markings yellow..................... 14
    Pale markings white....................... 15

  14. Yellow band on first abdominal tergite interrupted by black. Rear edge of abdominal black bands with 3 points or 1 central point, flanked by a pair of black spots ..... V. arenaria
    Yellow band on first abdominal tergite continuous. Black abdominal bands wide, with only a single faint point on the rear edge of each.........V. norvegicoides

  15. First and second abdominal tergites entirely black.......................... V. maculata.
    First and second abdominal tergites with a narrow whitish band at the rear and reddish marks at the sides................. V. albida
Persons using the key are reminded that it is accurate only for the worker caste. Queens are usually much larger than workers, and commonly have somewhat different markings. Males, which are similar in size and markings to workers, have longer antennae, and are best determined by structural differences in genitalia. The scape (basal segment) of the antenna and the "stripe behind eyes" referred to in the key are easily recognized in figure 229. The terms "tergite' and "sternite" used in the key are defined in chapter 4, in connection with figure 042.

The nesting behavior of Vespula species is widely variable. Certain species, such as V. maculata and V. arenaria, build aerial nests in trees, shrubs, and under eaves. The other members of the subgenus Dolichovespula, V. norvegicoides and V. albida, also sometimes build aerial nests in shrubs, but they commonly construct them on the ground in such materials as leaf litter and sphagnum moss clumps. These supraterrestrial nests differ from true ground nests in that the wasps do not excavate a soil cavity in which the nest is constructed.

Among the species in the subgenus Vespula, the most common nesting habit is terrestrial. Most of them, however, show remarkable adaptability, and supraterrestrial nests, nests in the voids of buildings, and even truly aerial nests are occasionally constructed. Some species (e.g., V. austriaca and V. arctica, both widely distributed in the United States and Canada) do not build their own nests, but are social parasites in the nests of other species. They do not produce a neuter (worker) form.

The color patterns actually seen when examining the species of Vespula depicted in figures 226 and 227 will not always be exactly like those shown, but will tend to approximate them, at least to the extent that there should be little difficulty in identifying a wasp of any of the species represented.

The Subgenus Vespula

western yellowjacket, Vespula pensylvanica (Saussure)

This is the most common and most pestiferous yellowjacket in California. The queens are about 20 mm long. The workers are about 16 mm long, and the typical pattern of their black-and-yellow markings distinguishes them from other species (plate VII, 3; figures 226, A, and 229). It is a pest because it is abundant and is often a scavenger. Although it has been observed to be predatory when prey species are abundant, it readily becomes a scavenging pest if native food supplies are inadequate. Completely predatory species of wasps are seldom important as pests, even when they are abundant. Vespula pensylvanicaoccurs throtighout the western states and adjacent Canadian provinces. In Mexico, it has been taken in the state of Michoacin at an elevation of 6,600 ft (2,000 m). It usually constructs subterranean nests, but occasionally builds them in wall voids, attics, and other aboveground sites. The biology and habits of V. pensylvanica were thoroughly investigated by Duncan (1939).

In certain years, V. pensylvanica appears in unusually great numbers in public camps in mountain areas, and sometimes surpasses mosquitoes and flies as an annoyance to campers. These wasp outbreaks are believed to result, at least in part, from a relatively mild winter and early spring (Bohart, 1941). Regional fluctuations in wasp populations are more likely to occur in the mountains than in the lowlands, for the insects are more adversely affected by severe spring weather. Campers sometimes leave their vacation places in large numbers because of numerous stings and the necessity of having to compete with yellowjackets for every mouthful of food eaten. In hot weather, the wasps seek water wherever it is spilled or in the wet sand of bathing beaches along the shores of mountain lakes, thus annoying bathers. In a discussion of one such outbreak of V. pensylvanica near Lake Tahoe, California, Bohart (1941) stated that persons stung were mostly those who hit or squashed the yellowjackets. A sting often results in a painful swelling. After the pain has subsided, there follows a period of itching. An ice cube or ice pack on the site of the sting will reduce both the pain and the swelling.

Vespula vulgaris (L.)

This is a common species, similar to V. pensylvanica in appearance (figure 226, B), and occurs in all the western states, throughout the northern states of the East and the adjoining areas of Canada, throughout western Canada, and in Alaska. In California, it is usually found north of Fresno. It has been reported from the state of Michoacán, Mexico, at an elevation of 6,600 ft (2,000 m) and on the western slope of Mt. Popocatepetl at 10,000 ft (3,000 m). As with V. pensylvanica, it is predatory, but often becomes a scavenger and is second only to that species as a pest in the western United States. The nest is almost always located near coniferous trees in partially rotted stumps, partially buried logs, or soil rich in organic matter in damp and shady locations.

Vespula atropilosa (Sladen)

This species occurs throughout the western states, northward into the southern halves of British Columbia and Alberta, and southward to Tijuana, Mexico. figure 226, C, shows that V. atropilose, as well as V. sulphurea (figure 226, F), usually has more yellow on its abdomen than the 2 preceding species. The nest is terrestrial.

Vespula sulphurea (Saussure)

This wasp is easily recognized by the 2 longitudinal yellow bars on the thorax (plate VII, 4; figure 226, F). It has been collected in many localities in most of California, but is most common in the northeastern area. It has also been found in southern Oregon, western Nevada, the Huachuca Mountains of southeast Arizona, and in northern Baja California. The nest is terrestrial.

eastern yellowjacket, Vespula maculifrons (Buysson)

This species (figure 227, A) closely resembles V. vulgaris, and is also ground-nesting, but does not occur in the West. It is found principally in the central Atlantic Coast states, and is common in deciduous forests, where it builds nests.

Vespula squamosa (Drury)

This is considered to be the most common ground-nesting yellowjacket in the southeastern states. It is easily identified by the pair of longitudinal, parallel, yellow stripes on the dorsal surface of the worker's thorax (figure 227, B). Although these stripes are also prominent on the queen, she is unique among Nearctic Vespula species by being notably different from her progeny in color and markings. Her abdomen is ambercolored, with some black markings, in contrast to the other castes in which the abdominal segments are black, bordered with bright yellow. This difference is so great that the queen was originally described as a separate species. Vespula squamosa has the ventral surface of the abdomen conspicuously marked with black, while the corresponding surface of its most closely related species, V. sulphurea, is bright yellow.

Vespula vidua (Saussure)

This species (figure 227, C) is a relatively common ground-nesting yellowjacket in the northeastern states. Note that it has much less yellow marking than the other species shown in figure 227. It has been found nesting within the walls of buildings on several occasions.

Vespula germanica (F.)

This European yellowjacket has become well established in the eastern United States. It somewhat resembles V. maculifrons, but is generally larger and has a greater proportion of yellow (figure 227, D). Also, V. germanica has black spots on at least 1 abdominal tergite, whereas V. maculifrons does not. Although this species is primarily a ground-nesting yellowjacket in Europe, it commonly nests in wall voids and other protected places in buildings in the United States. Its nests tend to be very large.

The Subgenus Dolichovespula

Vespula arenaria (F.)

This is one of the commonest yellowjackets in North America (figure 226, E). It occurs throughout the western states as well as the northeastern ones, and in most of Canada and Alaska. It is not found in the Plains states, and is absent in all but the northernmost areas of the southern states. The nest is aerial, and is often built under the eaves of houses (figure 235).

Baldfaced Hornet, Vespula maculata (L.)

The baldfaced hornet (figure 226, D) is the only black-and-white species among those shown in the figure. It is morphologically more similar to the yellowjackets than to the hornets. However, it resembles the hornets in behavior as well as in size. The worker caste cannot be separated from the queen caste on the basis of external morphology. There is a broad range of sizes in these females, but they are sometimes as large as the queen.

The white maculations are confined to the face, the tip of the abdomen, and to 2 stripes, 1 on each anteriolateral margin of the thorax. The species occurs throughout the United States, but is scarce in the southern half of the country. It is abundant in the northern half of the United States and the southern portions of the adjacent Canadian provinces from the Pacific to the Atlantic, and extends north into Yukon Territory (Miller, 1961), and also into Alaska. In California, this species occurs primarily in the north coast mountain ranges and at moderate elevations in the Sierra Nevada. It is not found in southern California. Nests of V. maculata are aerial, sometimes high off the ground, and are often 12 in. (30 cm) or more in diameter (Bohart and Bechtel, 1957).

Balduf (1954) had the rare opportunity to observe the construction of a nest of V. maculata against a windowpane in northern Minnesota. The wasps allowed the windowpane to serve in place of the usual "paper" envelope for one side of the nest. The activities of the wasps could be observed, and construction stages of the nest were photographed from the time its dimensions were 3.5 x 3 in. (9 x 7.5 cm) to the time the nest was completed at 8.4 x 6.8 in. (21.3 x 17.3 cm). Another such nest was built against a windowpane of a farm house in Illinois, and an account of the nest, with a photograph, appeared in the "State Edition" of the Chicago News on September 28, 1948. At its maximum, the nest was 24 in. (60 cm) high and 18 in. (45 cm) wide. Balduf observed that the wasps, like bees, manifested irritable and combative behavior on rainy days, and that food gathering was greatly curtailed on such days.

The Terrestrial Wasp Nest

The raw materials for constructing the "paper" from which the nest is made are vegetable fibers and salivary secretion. The fibers may be from the surface of rotten or weatherworn wood, the cortex of dead plants, fragments of caps of cocoons within the nest, cut away by young wasps when emerging, and from artificial products such as newspapers, paper bags, or cardboard signs.

The collected fibers are chewed and mixed with a salivary secretion to make a doughy mass. The queen selects the site for the nest and builds the first cells. Whether the nest is aerial or underground, the first structure to be built is generally a pedicel or suspensorium for the support of a small comb of cells. The pedicel is expanded into the first cell of the nest. Either simultaneously or after the first small comb is completed, a paperlike envelope is built around it, leaving just enough space between the envelope and the comb to allow for the movement of the wasps. An opening is left at the bottom of the envelope to allow for the entry and exit of the queen. Nestbuilding is continuous, from the time the first workers appear until the colony declines. Eight to ten or more tiers of combs can be built into a nest, all encased in an envelope that is enlarged as the combs are constructed (figure 230). As additional combs are built, many secondary suspensorium are attached to the nest envelope and comb above the one being constructed (figure 231).

Some entomologists, such as Andrewes (1969), believe that underground nests must have a root or stone in the roof from which the nest may be suspended, but excavations of nests of Vespula pensylvanica have revealed that this is not necessarily true. By the time the roof of the hollow has been wet by the queen and subsequently dried, it is quite hard and firm. It often contains gravel. The base of the pedicel is expanded to form a broad area of attachment to the roof. As the nest increases in size, many suspensoria are built from the "paper" envelope to the surface of the hollow, so the nest does not depend solely on the primary pedicel for its support.

Wasps that build subterranean nests do much more work on their nest sites than those that build aerial nests. They clear away leaves, grass, and other litter surrounding the entrance to the burrow (figure 232). They also do much excavating to enlarge the cavity in which the nest is built. Yellow acket nests may be over 30 cm in diameter. The excavation proceeds at a rate that depends on the speed with which the colony itself is developing. The clearance between the outer envelope of the nest and the wall of the cavity averages about 12 mm.

Whether the nests are excavated in naturally moist or in dry soil, the pellets of soil carried by yellowjackets when excavating them are either moist or appear to have been recently moist. Also, the interior of the nest cavity has the appearance of a dried mud surface. In the season of active excavation, worker wasps are abundant at sources of water. Duncan (1939) once observed a V. sulphurea worker returning at intervals of about 5 minutes to a particular spot at the edge of a small pond, each time drinking deeply before leaving. Wasps of other species were likewise observed doing the same thing, some drinking so much water that they experienced difficulty in taking flight. Water is apparently carried to the nest cavity, regurgitated on its walls, and the mud is then scraped off in pellets and carried away.

Much of the excavated earth is carried outside the burrow and dropped. Pebbles that are small enough to be moved but too large to carry very far may be dragged to the mouth of the burrow and left near-by. Duncan (1939) observed a V. pensylvanica worker carrying a pellet, in flight, at least 70 ft (21 m) from the burrow opening before dropping it. Some of the excavated mud is used to fill cavities leading out from the nest chamber, such as lateral rodent burrows. During the excavation of many V. pensylvanica nests in southern California, much of the excavated soil was found to have been used to reduce the diameter of rodent burrows in which the nests were constructed, where the burrows formed the entrance tunnels. Duncan took 3 qt (about 3 l) of dried pellets from a cavity left by a decayed root, which extended out from a nest cavity constructed by a colony of these yellowjackets. Sometimes there are 2 entrances to an underground nest, but the wasps use both entrances for ingress and exit.

As the end of the season of activity approaches, workers of most species begin to build cells of a larger size for the rearing of new queens. Queens are always reared in large cells and males and workers in small cells. Workers of V. pensylvanica may be reared in used cells. The number of adults successively reared in the same cell can be determined from the number of fecal pellets at the bottom of the cell (R. E. Wagner and D. A. Reierson, personal communication).

In extremely rare instances, wasps continue to live in and develop a nest into a second season in California. One such nest of V. pensylvanica measured 46 in. (115 cm) in one diameter and 40 in. (100 cm) in the other, and was 30 in. (75 cm) long. Only about half the height of the nest was occupied by combs, but there were 21 comb levels. The nest contained 4 gal (15 l) of wasps, including some newly transformed males and queens and 22 functional queen mothers, recognizable because of their worn condition.

Species that generally build their nests underground need not necessarily do so if adequately protected nest sites can be found aboveground. Figure 233, top, shows a V. pensylvanica nest that had been constructed in an attic. The lower figure shows the exposed combs of a nest that had been constructed between 2 studs in a house. The wasps in this nest were exterminated with a resmethrin aerosol, and then a considerable section of the outer wall had to be taken off in order to remove the extensive nest. In figure 234, the screwdriver shows the narrow entrance to a nest site chosen by a V. vulgaris queen in an old tree stump in Lassen National Park, California. Removal of some surface layers of wood revealed the nest in a cavity that had been excavated by the yellowjackets.

The Aerial Wasp Nest

The subgenus Dolichovespula contains the 2 species (Vespula arenaria and V. maculate) that are the most common aerial nestbuilders (figure 235). They often construct their nests on buildings, especially under the eaves (Wagner and Reierson, 1971). Most people are familiar only with aerial nests, although the majority of Vespula species build their nests underground. Wasps of the subgenus Dolichovespula tend to have smaller nests than those of the subgenus Vespula. The largest nest among the Dolichovespula ever observed by Duncan (1939) was one of V. arenaria a little over 30 cm in diameter and 35 cm long. On the other hand, a nest of V. pensylvanica with 5 comb levels that measured 25 and 40 cm in its diameters and 44 cm long was only a little larger than the average for the species. The Dolichovespula also build a smaller number of cells in their nests, but a larger proportion of queen (large) cells. For example, a completed nest of V. arenaria contained 1,199 small cells and 1,290 large cells, distributed among 5 combs. A much larger nest of V. pensylvanica at the height of its activity in mid-August contained 7 combs and 10,456 cells, all small. The colony had about a month longer to develop (Duncan, 1939). In nests of V. pensylvanica evacuated during the fall of 1970, Wagner and Reierson (1971) found an average of 15% as many queen cells as worker cells in mature nests.

Duncan (1939) observed that workers of V. arenaria (Dolichovespula) began to rear new queens as early as late June in central California, whereas none of the species in the subgenus Vespula in that area normally produced queens earlier than September and some not until late October.

The nests of Dolichovespula wasps show that the change from worker- to queen-cell construction is gradual, whereas with the subgenus Vespula it is abrupt.

Life History of Yellowjackets

In the early spring, the mated queens emerge from protected harborages in which they have spent the winter months. They feed on nectar, honeydew, and other sweets while flying about singly in search of a suitable site for a nest in which to start a new colony. These queens usually resemble the workers of their own kind, but are considerably larger in most species.

Egg. The queen of a vigorous colony may lay as many as 25,000 to 30,000 eggs. In the process, her wings may become frayed, and are sometimes worn down to mere stubs and most of her body setae are broken off as the result of the friction in inserting her body into the "paper" cells. The same cell may be used a second or third time for egg-laying. The milky-white eggs of the vespine wasps are about 4 times as long as broad, slightly curved, slightly narrowed and rounded at the anterior end, and more narrowed and less blunt at the posterior end. The posterior end of the egg is glued to the wall of the cell (Duncan, 1939). As with many Hymenoptera, the egg membrane is not shell-like, and does not maintain its form after the larva emerges.

Larva. At first, the larva is held in place at its posterior end by a mucus it secretes. It later becomes large enough to fill the lumen of the.cell and hold itself in place by friction. It can then be pulled out without in ury, and if the colony is asphyxiated, some of the larger larvae fall out of their cells. The mature larva is elongate and flattened dorsoventrally (plate VII, 3). The first abdominal segment is the broadest part of the body, which tapers abruptly anteriorly and more gradually posteriorly. Only about one-fifth of the total length of the larva is made up of head and thorax, compared with over a third in the adult. The full-grown larva is creamy white, except that the posterior section may appear somewhat blackish because of the dark intestinal contents.

Pupa. The mature larva spins a cell cap, and then voids from its intestine a blackish mass of accumulated intestinal wastes, called the meconium. This is attached to the bottom of the cocoon, or the bottom of the cell in the case of those species in which the base of the cocoon is incomplete. It dries into a brownish pellet, and the number of pellets at the bottom of a cell indicates the number of times it has been used for larval rearing.

Cocoons of the larvae that are destined to become queens are larger than the others and extend somewhat farther out of the cells. Pupation takes place in the cocoon. The legs and wings of the pupa are free from its body and, except for the pupa's whiteness and delicacy, its appearance is similar to that of an adult. The queens are larger than the workers, and the males have long antennae.

The total period required for larval and pupal development is about 1 month; about two-thirds of this period is required for the larval stage (Duncan, 1939).

Teneral Adults. The new adults, called "teneral" (soft and unpigmented), cut their way out of the cocoons, seek out the larvae in the comb, and bite the heads of these larvae to induce the secretion of a salivary liquid, a process called trophallaxis. This is the first food received by the newly emerged wasps. The larvae are said to make a rustling sound by scratching the walls of their cells in order to attract the feeding wasps (Andrewes, 1969). Soon afterward. the larvae are fed by the older workers in the nest on regurgitated sweets or bits of macerated and malaxated insects from which they suck the liquid contents. The teneral adults remain in the nest for a few days. If they are workers, they gradually assume the duties of nest-building and brood care. If they are queens, they are the founders of the next year's colonies. The males do much flying about after leaving the nest, visiting flowers for nectar, whereas the queens go into hibernation almost immediately after mating.

Control of Wasps

Wasps may be controlled by spraying directly into the nests if they are aboveground, or by pouring insecticide liquid into the openings of the nests of subterranean specics. This type of treatment must be done carefully, because the wasps defend their nests ferociously. A safer treatment is the use of poison baits in "bait stations" for the few species for which baits have been developed. This method of treatment also obviates the necessity for finding the wasp nests.

Sprays and Dusts

For the control of wasps that build aerial nests, various insecticide formulations have been made available in pressurized containers that shoot out a long, narrow stream of spray (Anonymous, 1962, 1970f). The author's associates, R. E. Wagner and D. A. Reierson, found resmethrin (SBP-1382®) to be spectacularly effective and superior to all other commercially available sprays of this type, as well as the safest. The liquid should first be directed into the opening of the nest to knock down insects as they attempt to leave, and then the entire nest should be sprayed.

For species that build their nests in the ground, the colony should be located during the day and then, for treatment, should be approached only in darkness, using a flashlight covered with red cellophane for light. Anonymous (1962, 1970f) recommend that 1quart (1 l) of insecticide liquid be poured into the nest entrance as quickly as possible. Dichlorvos 1%, chlordane 2%, or a suspension of 2 tablespoonfuls of carbaryl 5% wettable powder in a quart of water are recommended. If the nest is still active after 48 hours, pour in another quart of the same mixture. A 5% carbaryl dust blown into the nest opening has also been found to be effective.

Pouring insecticide liquid into a nest is accompanied by a certain degree of risk that can be avoided by wearing protective clothing or by directing a stream of spray liquid into the nest entrance from a distance of 5 or 6 m by means of a power sprayer. A quart (liter) of kerosene poured into the entrance will provide almost immediate extermination of all the adult yellowjackets that are in the nest (Wagner and Reierson, personal communication).

Cyanogas A dust, applied with a plunger duster, is very effective, almost instantly disabling all the wasps within the nest. Cyanide dust is extremely toxic, and should be used only by professional pest control personnel. Wagner (1961) worked out a control method for ground-nesting yellowjackets (Vespula pensylvanica) in a zoological garden and an adjacent picnic ground where they had been severe pests. He recommended that once a week, immediately after trash barrels were emptied, the inner surfaces, particularly near the rims, be sprayed with 0.75% dichlorvos. Since poor sanitation attracted the wasps, he stated that the trash barrels should be emptied as often as necessary to avoid filling them more than half full. Keeping the trash level in the barrels low exposed the toxicant residue to the wasps, and also tended to reduce the amount of trash dropped indiscriminately by the public. He also recommended that such a control should be begun early in the year before yellowjackets become numerous. The spray program should be continued through the summer season of greatest yellowjacket activity, thus insuring maximum control of these insects as well as flies and honey bees. If control is not satisfactory the spray program can be supplemented by searching the surrounding area for nests. They can be destroyed by means previously mentioned.

Bait Stations

A more effective and far more convenient method has been developed for the control of yellowjackets. Keh et al., (1968) were able to attract Vespula pensylvanica to poison baits of mirex in beef liver or undiluted fruit-drink concentrate. Yellowjacket workers carried the bait to their underground nests, and t.he mirex was detected in dead workers, males, queen, and larvae. Wagner and Reierson (1969, 1971) worked out a control program against the same yellowjacket species, using a bait consisting of fish-flavored cat food with 0.5% mirex. Results of tests with different pet-food bases disclosed that yellowjackets were very discriminating, and preferred Pacific mackerel over several other species of fish used in cat foods.

Mirex was the only insecticide of the 12 investigated that was not repellent to the yellowjackets. Using the figure "100" as the amount of cat food removed by the yellowjackets when no insecticide was added, the relative attractancy of the catfood-insecticide baits ranged from 1to 121. The latter figure indicated the relative attractancy of the mirex bait, which was the only bait more attractive than cat food alone. The workers carried the bait to their subterranean nests, killing the entire colony. To assist the foraging wasps in locating the bait station, an "attractant generator" was placed in it. This consisted of 25 ml of heptyl butyrate (Davis et al., 1967) in a 60-ml ointment jar with a cotton dental-roll wick protruding 1 cm through the lid. This ester was easily synthesized. It tripled the number of yellowjackets attracted to the bait station. A proprietary bait station based on these findings became available in the summer of 1971.

The first yellowjackets to be seen in the spring are the overwintering queens. They feed on nectar, honeydew, and other carbohydrates. Carbohydrate baits were not tested, since they might have the disadvantage of attracting honey bees and other nontarget insects. When the workers appear, they search for proteinaceous food to feed the developing larvae in the nest. There follows a long period when a protein bait can be used that attracts yellowjackets and practically no other insects. The virgin queens that appear in the fall search for overwintering sites at the time the colonies are rapidly declining, and only the newly mated queens survive the winter.

When protein foods are being scavenged by yellowjackets, the baiting method is safe, convenient, adds practically no insecticide to the environment, and is harmless to all species but V. pensylvanica and V. vulgaris. The suppression of yellowiacket populations does not upset the "balance of nature". Only the nests within flight range of baited residential areas, parks, zoos, picnic grounds, camps, and recreation areas are eliminated. Most yellowjacket species are beneficial predators, and are not attracted to protein-based baits.


The genus Vespa is represented in North America only by the giant hornet, V. crabro germana (Christ), also sometimes called the brown hornet or European hornet. This large, robust, brownand-yellow wasp (plate VII, 5), about 22 mm long, was introduced from Europe, and now occurs sparingly in the Atlantic seaboard states. According to Duncan (1939), Vespa spp. are the "true hornets," and are characterized by having the head swollen behind the eyes and the ocelli remote from the margin of the head. The nests of the giant hornet may be in hollow tree trunks, in buildings, or in other sheltered places, but occasionally in the ground or in aerial situations. Vespa crabro is the only wasp in the United States that is known to use fibers from the cortex of living plants as materials for nestbuilding, and it has caused injuries to dahlias and various shrubs when obtaining these fibers. When this hornet builds its nest in the open or in cavities in soft earth, it constructs an envelope around the combs like that found in yellowjacket nests. Its subterranean nests lack envelopes only when they are built in very hard and stony ground in which the stones prevent their normal enlargement. In hollow trees, there may be no envelopes at all, except perhaps for a few rudiments above the first comb and to partly close the access hole to the hollow interior.

The term "hornet" is also applied to Vespula maculata (described earlier) because it is the only species of Vespula in North America that resembles the giant hornet in size and behavior. Its white markings make the term "yellowjacket" inappropriate.


The wasps of the genus Polistes are sometimes called "paper wasps" because of the paperlike material from which their nests are made, but that name is equally appropriate for other vespids. The author suggests that they be called "umbrella wasps," based on the shape of their nests. The closely related but relatively unimportant wasps of the genus Mischocyttarus should then also be called "umbrella wasps." The genus Polistes is world-wide in distribution, and in Europe and North America its colonies outnumber those of all other social wasps combined. Polistes may be distinguished from Vespula by the presence of a distinct lobe on the hindwings and by the spindleshaped abdomen, which tapers at both ends and is never truncate at the base. A key to the California species of Polistes was prepared by Bohart and Bechtel (1957).

Whereas the Vespula species are,best known as pests in resort areas, parks, picnic grounds, and zoological gardens, Polistes are better known as pests in orchards and vineyards. They are often seen on or near their nests in fruit trees, feeding on the juices of injured fruits, or on flowers.

As with Vespula, the nests of Polistes are begun in the spring by fertile, overwintering females. The females are sometimes joined by one or more other fertile queens that assist in the nest's construction and maintenance. These additional reproductives are relegated to more or less worker status, for the founding queen maintains dominance and is the only egg-laying individual. In such cases, should the dominant queen die, one of the other fertile females can take over her duties and the nest will survive. There is no appreciable difference in the size and appearance of egg-laying queens and the workers.

The nests of Polistes differ from those of Vespula in that they are single-layered with the cells exposed. The nests are umbrella-shaped, and are generally supported by a longer pedicel (figure 242) than the nests of vespids. They are never completely enveloped in paper. Although they are commonly suspended from the branches and twigs of trees, they are also often suspended from the eaves and attics of houses or the ceilings of barns and sheds, more so than the aerial nests of Vespula. Polistes nests just as those of Vespula, may be found in almost any imaginable location. A nest of P . exclamans exclamans was transported from Pennsylvania to Germany inside the bumper of an automobile. Nineteen wasps emerged from the nest, along with 15 specimens of a hymenopterous parasite, Elasmus polisti Gauss (Gauss, 1972). Eberhard (1969) suggested that the pedicel between the nest and the attachment surface might lessen the probability of discovery of the exposed brood by predators, and that a single narrow access to the nest might result in more effective defense against them. She observed ants being effectively repelled by umbrella wasps when the ants attempted to cross the narrow pedicel.

Polistes fuscatus (F.)

This is the most common North American species of Polistes, and occurs with its varieties throughout the United States. It also extends into southern Canada, Mexico, and Central America, and has been accidentally introduced by man into the Bermudas, Jamaica, Barbados, Society Islands, and Hawaii (Bequaert, 1940). It is the most abundant and widespread umbrella wasp in California having been recorded in 51 of the state's 60 counties and from sea level to over 8,000 ft (about 2,400 m) elevation. The most widespread subspecies, P. f. aurifer Saussure, ranges from British Columbia to southern California, where it merges with P. f. centralis Hayward. The latter extends south into Baja California and east and northeast as far as Texas, New Mexico, and Colorado. At the eastern extremities of its range, P. f. aurifer intergrades with P. f. variatus Cresson in northern Washington and Idaho and with P. f. utahensis Hayward in the foothills of the Rockies, partictilarly in Utah (Bohart and Bechtel, 1957).

Polistes fuscatus aurifer is about 18 mm long. The face and the bulk of the abdomen are bright yellow (plate VII, 6; figure 236). Only the first 2 anterior bands of black are conspicuous on the abdomen. The thorax is black except for 6 narrow, yellow stripes: 2 marginal stripes on the pronotum, 2 transverse stripes on the mesonotum, and 2 lateral stripes on the metanotum. The upper surfaces of the coxae and femora are brownish, but the remaining surfaces of the legs are yellow.

The nests of P. f. aurifer (figure 237) are often found attached under eaves and even inside attics. Umbrella wasps in general are more apt to seek man-made structures for nestbuilding than are the species of Vespula that build their nests aboveground. This is to be expected, in view of the fact that Polistes nests do not have a strong and complete envelope, such as that possessed by Vespula nests, to protect them from the elements.

Polistes fuscatus centralis (figure 238) ranges in color from the red and yellow of the more typical forms to nearly all yellow. In-California, it occurs in the southeastern area as an inhabitant of creosote bush (Larrea divaricata) and prairie, plains, and desert grassland areas (Bohart and Bechtel, 1957). In Baja California, these wasps have at times been so numerous in cotton fields that they destroyed populations of lepidopterous larvae before the insecticides applied had time to take effect (Snelling, 1954).

Polistes apachus Saussure

This wasp (figure 239) has been referred to as the "Apache wasp" (Simmons et al., 1948). it occurs in the central valleys and in southern California, and also in Texas and adjacent areas to tile north, west, and south. It appears to have been introduced into California from Texas about 1920, and has been gradually extending its range there since that time (Bohart and Bechtel, 1957). It has become established in some urban areas of southern California as the primary polistine species nesting under the eaves of buildings. It has a tendency to build its nest close to that of the previous year, or at least in the same building. In one case, this habit was observed for 10 years, and during that period the wasps shunned adjacent buildings of similar construction (Gibo, 1972). This habit accounts for the occasional finding of as many as 12 nests in the attics and / or eaves of some buildings.

In Texas and adjacent regions, P. apachus is primarily associated with mesquite and grassland rather than with wooded areas. Nests are large, circular, and contain about 150 cells. The frequency with which this wasp builds its nest in fruit trees and vines, and its pugnacity when disturbed, have resulted in its reputation as an agricultural pest.

Description. Polistes apachus attains a length of as much as 20 mm. The basic color is golden brown. The pronotum is bordered with a thin, yellow stripe. The mesonotum has 2 transverse stripes of yellow-the anterior stripe narrow and the posterior stripe broad. The abdomen has alternate stripes of golden brown and yellow. On some wasps, the 2 colors are about equal in extent, and in others, one or the other color may predominate.

Biology and Habits. Simmons et al. (1948) studied the biology and habits of P. apachus in fig orchards. They found that in the spring, 2 to 6 wasps cooperated in the building of a single nest, and that such nests initially harbored from 1 or 2 to as many as 6 or 7 queens. They found that often new nests were rebuilt within a week in fig trees in which they had been removed. Nests in fig orchards were said to average about 13 cm in diameter and to contain 320 cells, over twice the number- reported by Bohart and Bechtel (1957). Combs as large as 15 x 20 cm were found.

Polistes dorsalis californicus R. Bohart

This is the dominant subspecies of P. dorsalis (F). It has light-red and yellow markings, and practically no black (figure 240). This form most Commonly hibernates under loose bark of cottonwood or eucalyptus and in company with P. fuscatus aurifer. Although its nests are usually small, Bohart (1949) collected an elongate nest with a double pedicel near the middle and containing about 250 cells. The typical species occurs at low to moderate elevations in California, from Shasta County south, and also occurs in southeastern Arizona. In southern California and Arizona, this subspecies overlaps with it.

Polistes exclamans arizonensis Snelling

This subspecies ranges from the state of Sonora, Mexico, into Arizona as far north as Phoenix and into the extreme southeast of California. According to Bohart and Bechtel (1957), it can be recognized by its 'brownish-red color, moderate size, and spotted antennae in the female" (figure 241). This wasp is a nuisance in citrus orchards. Laborers have refused to work in infested orchards, particularly to pick fruit. The stings are very painful, and some workers who were stung have had to be hospitalized. In Mexico, some orchards were abandoned because the wasps became so abundant. In the Salt River Valley of Arizona, in some cases up to 20% of the fruit has remained unpicked because of umbrella wasp infestations. From 1 to 26 nests have been observed per tree. The nests (figure 241) occur inside the foliage canopy of a citrus tree. They are elongate, 15 to 35 cm long and 5 to 15 cm wide. They are positioned vertically, instead of horizontally as with most other Polistes species, and face the interior of the tree. There may be from 100 to more than 200 wasps per nest. Numbers of them will attack if the nest is disturbed (Hopkins, 1955).

Polistes exclamans exclamans Viereck

This subspecies (figure 242) is common in the southeastern and Atlantic seaboard states. It is not very pugnacious, but inflicts a potent sting. Although variable in color, it is always well marked, sometimes profusely, with yellow. The pendulant, umbrella-shaped nest (figure 242) of this wasp was removed from the eaves of a house in New Jersey. It has the typical form of the nests of most species of umbrella wasps-single-layered and never completely covered with a "paper" envelope, as are the nests of Vespula.

Control of Umbrella Wasps

In attempts to control Polistes apachus in fig trees, Simmons et al. (1948) tried poisons with beef liver and with honey, as well as proprietary ant poisons, but without success. Dusting the nests with 10% DDT dust (available at that time) proved to be successful.

Control of Polistes exclamans arizonensis in citrus trees was obtained with a spray of 0.5 pt (about 0.25 l) of 100% Thanite® to 5 gal (19 l) of spray oil. This was applied to the wasps and their nests with a 2- or 3-gal (7.5- or 11-l) compressed-air sprayer (LaFollette, 1952). Also, 1% Thanite in base oil (deodorized kerosene) may be used (Hopkins, 1955). Later on, DDT, lindane, and chlordane were used to control this species, but they killed the wasps too slowly. After being hit by the sprays, they became highly agitated for an hour or so before paralysis ensued. During this period, they flew around rapidly and attacked anyone within 30 m of the sprayed nest.

Wene (1969) recommended the substitution of some pesticide that would paralyze the wasps more rapidly. He compared 4 preparations, 3 used at 1 Ib per 100 gal (0.45 kg per 378 l) and another (chlordane) used at 1.5 Ib per 100 gal. When sprayed with propoxur (Baygon), the wasps started dropping after a minute, and one could pick them up without being stung. After 5 minutes, 80% were completely paralyzed, and after 15 minutes, all were apparently dead. After spraying with dichlorvos, the wasps started dropping in 2 minutes. Once on the ground, they crawled around without making any attempt to fly. In an hour, all were apparently dead. With Gardona, the wasps started dropping to the ground within a few minutes, then crawled around without attempting to fly. In an hour and a half, 32%were dead and the remainder were paralyzed. Gardona is one of the safest insecticides to humans, with an acute oral toxicity of 4,000 to 5,000 (tables 1 and 2, chapter 2). When sprayed with chlordane, the wasps flew around vigorously or, if they dropped, they were nevertheless quite active , and in fact they flew away within an hour; 2 days after application, no live or dead wasps were seen. When propoxur, dichlorvos, or Gardona were used, many dead wasps were seen on the ground.

Most commercially available aerosol sprays that contain pyrethrins are extremely effective in knocking down umbrella wasps within a few seconds. Also, synthetic pyrethrins have been used with good results. Pyrethrins and pyrethroids appear to be the best insecticides for control of umbrella wasps. This is in sharp contrast to the relative ineffectiveness of most pyrethroids against yellowjackets and hornets, although resmethrin is effective. One is likely to arouse the pugnacity of yellowjackets with pyrethrins, and to be stung by these wasps before they die (R. E. Wagner, personal communication). The best time to treat wasp nests is in the early morning or at night, when most of the workers are in the nest. The nest should then be knocked down in order to prevent its re-use (Wagner and Reierson, 1971).


In this subfamily, Mischocyttarus is the best-known genus. This genus can be distinguished from Vespula and Polistes by the slender, petiolate basal abdominal segment and the shape of the gaster (plate VII, 7; figure 243). There are at least 183 species in Mischocyttarus, and it ranges from northern Argentina northward to British Columbia in the West and through the West Indies to Florida in the East (Wilson, 1971), but there are only 2 species in the United States.

As in the case of the pedicels of Polistes nests, as observed by Eberhard (1969), the pedicels of Mischocyttarus nests may contain a repellent to keep scouting ants from gaining access to the nest and discovering the brood. The Neotropical M. drewseni Saussure has a gland at the base of the terminal sternite that excretes the repellent onto a tuft of hair. The tuft is rubbed against the pedicel to deposit the repellent substance (Jeanne, 1972).

Mischocyttarus flavitarsis flavitarsis (Saussure) (figure 243) is the species found in California, where it is common, widespread, and found from sea level to 9,000 ft (2,700 m) elevation. It is 16 to 20 mm long, and is colored orange-yellow, reddish, and black. Females are sometimes found Ihibernating under bark together with Polistes fuscatus aurifer and P. dorsalis californicus (Bohart and Bechtel, 1957), and have also been found in an abandoned nest of Vespula arenaria (Smith, 1944). The nests of M. f. flavitarsis may be found suspended from the eaves of houses, branches of trees, and similar supports, and are almost indistinguishable from the nests of Polistes, but are usually somewhat smaller.


There are many species of wasps commonly referred to as "solitary wasps,"although among these, in the subfamily Eumeninae, there are species with subsocial behavior (Wilson, 1971). In general, however, the solitary wasps do not have a socially organized life, each female making a burrow or other form of nest for herself and caring for her own offspring. She stings her prey (insect or spider) to paralyze it, and usually brings it back to a cell in her nest, oviposits on it, and seals the cell. Most species will repeat the process until they have prepared a number of cells in the same nest, each with food for larvae. Some "spider wasps' (Pompilidae) will attack and paralyze a spider in its own cell or burrow, oviposit on it, and leave it in place.

There is a great variety of forms and sizes of solitary wasps, ranging from about 6 to 38 mm in length. They vary in color from dull black or brown to brilliant red, yellow, or blue. They have stingers, but their venom is generally not so potent as that of the social wasps, although the mutillids, psammocharids, and some others can inflict a very painful sting. As stated earlier, there are a few species of solitary wasps in the Vespidae, although its species are mainly social.

Genus Pseudomasaris (Vespidae: Masarinae)

Wasps of the genus Pseudomasaris build hard nests of mud, or sand and mud, attached to twigs or rocks., Each nest is elongate or globular, and contains several cylindrical cells (figure 244). Unlike other wasps, which provision their cells with meat, the species of Pseudomasaris provision them with pollen and nectar as do the bees (Hicks, 1927; Bequaert, 1929). They look like vespine wasps in having a black body color marked with yellow. Pseudomasaris vespoides (Cresson), the largest species, occurs throughout the West, and has been recorded as far east as South Dakota. It attaches its nests to twigs or rocks in California, but only to rocks in Colorado (Hicks, 1927). Adults may be seen on Penstemon, Phacelia, and other flowers. Pseudomasaris edwardsii (Cresson) also is found throughout the West, and is the species most commonly seen in southern California, usually on Phacelia flowers. Less commonly found is P. wheeleri Bequaert. The adults of P. wheeleri are 13 to 17 mm long, and black, with numerous and rather variable sulfur-yellow markings. The mesonotum has 2 complete or interrupted longitudinal yellow stripes (figure 244). The eyes are bulging in the male. The yellow markings are more extensive and more variable in the female than in the male (Bequaert, 1929). They visit Eriodictyon and Penstemon flowers.

Potter and Mason Wasps (Vespidae: Eumeninae)

Most solitary vespids are in the subfamily Eumeninae, the potter and mason wasps (Muesebeck et al., 1951). These wasps vary from 9 to 20 mm in length, and are dark, with white, yellow, orange, or red markings. The females have 12-segmented antennae, and those of the males have 13 segments. The wings are folded longitudinally when at rest, and the middle tibiae have 1 apical spur, as in all other vespids. The affinity of these wasps to other vespids can be seen in some aspects of their behavior as well as in morphology. They always lay their single egg in an empty cell, often suspending it from the wall by a slender filament, whereas other mud-users lay their egg on the prey. The potter and mason wasps place from 1 to 12 caterpillars in their nests, soon after the egg is laid and then seal them (Evans, 1963).

The best-known Eumeninae are the potter wasps (Eumenes). They differ from most other genera in the subfamily by having a very narrow, elongated first segment of the abdomen. Eumenesiturbide pedalis Fox (figure 245) is 13 or 14 mm long and predominantly black, but with prominent yellow markings, particularly on the abdomen, and with the tibiae, tarsi, and apices of the femora dull red (Fox, 1894). It is distributed throughout the western states and in western Canada and Mexico (Muesebeck et al., 1951).

All species of Eumenes build little clay pots for nests, and usually attach these to twigs, as shown in the figure. They provision the nests with caterpillars. The pots are globular, and have thin, short necks with expanded lips, resembling miniature jugs. Evans (1963) stated that they were among the finest examples of insect architecture. This cannot be said of the work of some other genera of the subfamily, such as Odynerus, Rygchium, and Ancistrocerus, which may use mud merely as a partition between cells in a hollow twig, abandoned ground-bee burrow, or Polistes cell (some species make their own ground burrow), or they may make mud cells on rocks.

Spider Wasps (Pompilidae)

These are medium-sized to large, metallic dark-bIue or reddish wasps, with iridescent wings and long, spiny legs. They all provision their nests with spiders, but unlike the mud daubers, they use only 1 spider in each nest. Unlike other solitary wasps, the pompilids catch their prey before preparing their nests. The spider is generally paralyzed by a single sting into the underside of the body in the region in which the nerve centers are clustered together. However, some spider wasps give the victim numerous stings at random to slow it down before administering the principal ventral sting. Unlike most solitary wasps, the stings of which are not very painful to humans, the sting of a spider wasp is very painful. The wasp drags the paralyzed spider while she backs up to a location suitable for digging a nest hole, hides the spider, excavates the nest, and then pulls her prey into the hole and lays an egg, usually on its abdomen. After the egg hatches, the larva gradually devours and finally kills its host. The habit of capturing prey before preparing the nest has its disadvantages, for the paralyzed prey may be stolen by some other insect (such as ants or another pompilid) while its captor is digging. One species places its prey in the crotch of a plant while digging, and another hides it temporarily in a shallow grave to decrease the possibility of theft. After oviposition, the burrow is closed with earth, and the entrance is tamped down with the apex of the wasp's abdomen. Some species disguise the entrance by placing pebbles or other objects on and around it (Andrewes, 1969).

Tarantula Hawks, Pepsis spp. (Pompilidae)

These are very large wasps, metallic velvety blue-black throughout, with violaceous, amber, or red wings. They prey on trapdoor spiders and tarantulas. They have long been well known in the southwestern United States, and were further popularized in Disney's remarkable film about life on the desert, in which a fierce struggle between a tarantula hawk and a tarantula was one of the exciting episodes. When the spider rises on its hind legs in defense, it exposes its vulnerable ventral area, and the wasp disables it with a rapid thrust of its stinger.

Pepsis formosa (Say) is one of the largest and best-known species of tarantula hawks. It is 25 to 45 mm long, steel-blue and black throughout, with fiery-red wings. Essig (1926) stated that P. formosa occurred in "Mexico, Texas, New Mexico, Arizona, and southern California" (it was originally described from Arkansas), but it is now known that the species does not occur in California. Pepsis thisbe Lucas (= sherillae Hurd), a species closely resembling P. formosa, occurs in all but the northern third of California. Other species of the genus found in California are chrysothemis Lucas, pallidolimbata pallidolimbata Lucas, pallidolimbata smithi Hurd, elegans Lepeletier, pattoni Banks, mexicana Lucas, and mildei Stål. The latter species (figure 246) may be distinguished from all the other known species of Pepsis in California by the antennae having at least the apical segments, but usually the apical three-fourths of the antennae, orange or reddish orange, and by the yellowish-brown wings, with bands of dark brown (Hurd, 1948).

A curious characteristic of the genus is that the antennae of the females are curled, whereas those of the males are straight. This difference is accentuated in mounted specimens, in which the antennae of the females form a complete loop.

Other Pompilids

Aside from the tarantula hawks, a few other species of pompilids have attracted attention in the West. Pompilus luctuosus Cresson is 10 to 12 mm long, metallic blue-black, with smoky wings having a violet iridescence. It occurs throughout boreal North America. Another species, Psorthaspis planata (Fox), has been reared from the nests of a trapdoor spider (Davidson, 1905).

Mud Daubers (Sphecidae)

Mud daubers are medium-sized to large wasps, with petiolate abdomens, the petioles long and slender as is characteristic of the Sphecidae. They are sometimes called threadwaisted wasps. Probably the most familiar of their nests are those made of mud or clay and attached under bridges, against houses, or under eaves, in garages that are commonly left open, or in barns or sheds. Cylindrical cells of mud are built side by side until they make a mass that may be the size of a fist. The entire structure is plastered over to make a relatively smooth and uniform outer surface. The cells within the nest are provisioned with insect larvae or spiders which have been paralyzed by the female's venom, and a single egg is laid in each cell. The larvae feed on the paralyzed prey. A larva can mature in 3 weeks and then spins a cocoon, but does not actually pupate until the following spring. Mud daubers rarely sting, and do not defend their nests. They can be eliminated by tearing down their nests.

Black-and-Yellow Mud Dauber, Sceliphron caementarium (Drury)

This species (figure 247) occurs throughout boreal North America. It is 15 to 17 mm long, dull black, with the bases of the antennae, collar, scutellum, a portion of the metathorax, petiole, and portions of the legs bright yellow. Its nests (like the one shown in the figure) are common in attics, porches, and outbuildings. The cells are 25 to 36 mm long, and there may be 6 or more in a nest. The whitish larvae are 10 to 14 mm long.

Biology. This has been investigated in great detail by Rau and Rau (1918) and Shafer (1949). A single cell is provisioned with several spiders. In one cell containing 8 spiders, 2 died in 8 days, 1 on the tenth day, 3 on the fourteenth, 1on the fifteenth, and 1 on the thirty-second day. Crab spiders are preferred, but black widow spiders are sometimes used to provision the cells.

Chalybion californicum (Saussure)

This beautiful wasp (figure 248) is 12 to 18 mm long, metallic blue, blue-green, or blackish, with blue wings. It occurs throughout the United States. It has been reported that this species does not build its own nests, but occupies those built by Sceliphron caementarium. It carries water to the nests of the latter to soften the mud at the cell entrances, and opens them with its mandibles. It then empties the cells of all the spiders its host stored in them, and replaces them with spiders of its own. An egg is laid on the first paralyzed, replaced spider, others are placed on top of the first one, and the cell is sealed (Muesebeck et al., 1951; Matheson, 1951).

Digger Wasp, Ammophila murrayi Menke (Sphecidae)

This ground-nesting wasp (figure 249) has habits characteristic of the genus, and is commonly seen in southern California at moderate elevations. It is 16 or 17 mm long. The head and thorax are black. The first 2 abdominal segments are long and petiolate, the first black and the second rusty red-brown. Dorsally, the first 2 gastral segments are red-brown and the others are black. (In some species, the abdomen is orange or yellowish.)

Habits and Biology. The members of the genus Ammophila are very slender, with petiolate abdomens. They drag caterpillars into burrows they have dug in the ground, and their larvae feed on the paralyzed prey. These wasps were made famoils by Peckham and Peckham (1905), who described their habits in great detail, including their use of a "tool." They temporarily close the tunnel leading to their nests while they are out hunting caterpillars, using a pebble or a piece of twig as an implement. Also, after the nest is provisioned and the tunnel is blocked with soil, the wasp will seize a pebble in her jaws and hse it to tamp down the soil at the entrance.

Cicada Killer, Sphecius speciosus (Drury) (Sphecidae)

This is a large insect, up to 40 mm long. It has a black body marked with yellow, like the yellowjackets, but is much larger (figure 250). It occurs in the United States east of the Rocky Mountains and south into Mexico, preying on many species of cicadas (Dow, 1942; Damback and Good, 1943). After paralyzing her prey with her stinger, the female places it at the bottom of a long burrow she has dug and lays an egg on it. The burrow is about 12 mm in diameter, so a considerable amount of earth is removed and thrown out to form a mound. When this happens in a lawn, the wasp becomes a pest. The female will not sting unless she is handled, but sometimes stings people painfully who are working on lawns, or barefooted children who are playing on them. The males only buzz around people, but do not sting.

Other species of Sphecius found in the United States are S. convallis Patton, ranging from Kansas to California and Baja California, and known to prey on cicadas; S. grandis (Say), recorded from Tennessee, Missouri, Arkansas, and throughout the West; and S. hogardii (Latreille), that occurs in the southern tip of Florida and in the West Indies (Muesebeck et al., 1951).

Control of Digger Wasps

For the control of cicada killers and other solitary, ground-nesting wasps, sprinkle 10% chlordane dust at the entrances to their burrows (Anonymous, 1970f).

Sand Wasps (Bembicidae)

Bembicids have a beelike form, but are solitary in habit, and nest in the ground. They are large and robust, 11to 20 mm long, smooth or finely pubescent, and are black or grayish, with greenish-yellow, orange, or red markings and abdominal bands. They have relatively large heads and especially large eyes. The abdomen is not petiolate, but has a broad base and tapers to a point posteriorly (Essig, 1942; Andrewes, 1969). These insects build their nests in sunny, sandy places. Their forelegs are fossorial, and have a fringe of long, inner hairs for moving the sand. The males (sometimes the females also) may dig shallow burrows in the sand in which to spend periods of inactivity. The nesting burrows are 12 to 24 in. (30 to 60 cm) in depth, and each contains 5 or 6 larvae in a single cell. These are fed daily, nearly all species receiving masticated flies. They hibernate in thick, oval cocoons, and the adults emerge in spring and early summer. Rau and Rau (1918) described the sudden emergence of thousands of sand wasps (Bembix nubilipennis Cresson) in a "sand-lot" baseball field in St. Louis (Missotiri) to participate in a "dance" 6 to 20 in. (15 to 50 cm) from the ground. They counted 44 emergence holes in an area about a meter square where none had been seen before the simultaneous emergence. This species brings small flies to its nest while the developing larvae are small, and larger ones as they grow larger (Muesebeck et al., 1951).

The 2 most important genera are Bembix and Alicrobembex. [The generic names Bembix and Microbembex appear to be inconsistent in their spelling. They are given here just as they were originally named, and as they are recogiiized by entomologists]. These are black, usually with yellow markings similar to those of yellowjackets. The Bembix species provide their nests with flies, many of which are tabanids and muscoid species. In California, Bembix americana F., B. amoena Handlirsch, and B. occidentalis (Fox) are the most abundant and widespread, although Bohart and Horning (1971) included 8 others, as well as some varieties, in their keys to California species. These are well known to collectors of wasps, possibly because of their large size and bright markings. Microbembex species are relatively small-sized, averaging 11 to 13 mm long, whereas Bembix species average 15 to 20 mm. They often occur in large colonies in areas of fine sand. They do not capture live prey as do other sand wasps, but provision their burrows with a wide variety of dead or moribund arthropods. Microbembex monodonta (Say) is the best-known species. It ranges from Canada to Panama, east of the Continental Divide. A closely related species, M. californica R. Bohart, occurs west of the Continental Divide in the United States and south to Sonora and Baja California in Mexico. The markings are yellow in the male and whitish to yellow in the female. Bohart and Horning (1971) included 4 other species of Microbembex in their keys.

Bethylid Wasps (Bethylidae)

These are small to medium-sized, usually metallic-bronze wasps. Either or both sexes of a species may include winged and winglessm individuals. The larvae are commonly endo- or ectoparasitic on the paralyzed or dead larvae of beetles, moths, and butterflies.

In 1927, a tiny black wasp of the genus Epyris, which inflicts a severe sting, was reported from Yolo County, California (von Geldern, 1927). These wasps were said to appear in large numbers in the fall after a warm spell, invade houses, and get into bedding and clothing, where they stung when crushed against the skin. Individuals within a family varied greatly in their reactions, the most sensitive suffering general systemic disorders over a period of about a half hour, including itching, cramps, diarrhea, marked prostration, weakness, and sweating. The wasp was Iater identified as Epyris californicus (Ashmead). It is occasionally reported to sting people in the lowland delta area in northern California. It is believed to parasitize the larvae of tenebrionid beetles (Essig, 1932, 1942). Muesebeck et al. (1951) recorded the species as occurring in California and Arizona.

Cephalonomia gallicola (Ashmead) occurs in the eastern United States, Europe, and Asia, and is probably cosmopolitan. Certain beetles, such as Stegobium paniceum and Lasioderma serricorne, which commonly infest stored products in the household, are hosts of this wasp. Adult wasps are likely to become abundant in houses with a persistent infestation of the beetles, and there have been many reports of the human occupants being stung. Other bethylid wasps of the genus Sclerodermus parasitize cerambycid beetle larvae infesting the woodwork of houses, and the adult wasps have often been reported to sting people (Muesebeck et al., 1951).

Velvetants (Mutillidae)

Mutillids or velvetants are medium-sized, brightly colored insects that resemble ants, but lack the node that is characteristic of the petiole of the ant. There are many species, and most occur in the West and South. Their bodies are bIack, but are densely clothed with white, yellow, golden, orange, or bright-red hairs that give the insects a velvety appearance. The females inflict very potent stings, and can make a queer squeaking noise when captured. The males usually have wings, and have straight, 13-segmented antennae; the females are wingless, and have curled, 12-segmented antennae.

Biology. Unfortunately, little is known about the biology of these interesting insects. The larvae are external parasites on larvae and pupae, principally of wasps and bees, bat a few species also feed on certain beetles and flies. The female oviposits on the prepupal or pupal stage of its host, the larva devours its host in a few days, and the cocoon is spun within the pupal case of its host. Some species are believed to dig nests in the soil and provision them with insects, but more are believed to be parasitic in the nests of wasps (e.g., Chalybion) and ground-inhabiting bees (Bombus and Nomia) (Essig, 1926, 1942). Some species are known to prey on honey bees (Matheson, 1951).

Descriptions. Following are descriptions of some of the California mutillids. The colors given always refer to the dense covering of hairs, for the body itself is always black or nearly so. The female of Dasymutilla satanas Mickel (figure 251) is about 20 mm long, and is clothed with long, erect, pale-ochraceous hairs, except that those on the legs are black. In the male, which is 13 mm long, tergites 3 to 6 are clothed with light-fulvous pubescence. The male was once believed to be a distinct species (Dasymutilla mimula Mickel) (Mickel, 1928) until it was found mating with D. satanas females by Barr and Hurd (1947). Dasymutilla aureola (Cresson), 12 to 13 mm long, varies from almost white in Inyo and Tulare counties to orange or almost scarlet in coastal California as far north as San Francisco (Hurd, 1951). In D. californica (Radoszkowski), the female is 8 to 14 mm long, and brick-red. It has been recorded from New Mexico, Colorado, Utah, and California. In D. gloriosa (Saussure), the female is 13 to 16 mm long, has long, white hairs, and is commonly known as the "thistledown mutillid". It occurs in central and southern California and eastward through Arizona, New Mexico, and Utah. In D. sackenii (Cresson) in southern California, approximately the anterior half of the male's abdomen is black and the remainder is white. In the female, approximately the anterior fourth of the abdomen is black and the remainder is white. Both sexes have white hairs on the dorsum. In northern California, the white dorsal vestiture changes to yellow. In D. flammifera Mickel, individual specimens vary from bright scarlet to nearly ocher, some of the latter being difficult to distinguish from the yellow females of D. sackenii by the nonspecialist (Hurd, 1951). The male of Pseudomethoca propinqua (Cresson) is 9 mm long, the dorsum of the thorax is black, the vertex and apical margins of the abdominal segments are golden, and the wings are dark. The female is similarly colored, and is 8 to 12 mm long. This species has been recorded from Minnesota south to Texas and west to Alberta and California (Essig, 1926; Muesebeck et al., 1951).

Scoliid Wasps (Scoliidae)

The scoliids are large wasps, with large heads and short antennae. The legs are stout, and the tibiae of the middle pair have only 1spur, whereas those of vespine wasps have 2. The general background color is black, but with yellow, orange, or red bands or patches, principally on the abdomen. The females are generally larger and more brightly maculated than the males. They do not dig their own burrows, but attach their eggs to a scarab larva and construct a crude cell around it (Essig, 1926; Hurd, 1952).

Campsomeris tolteca (Saussure) appears to be the dominant scoliid in southern California, and is commonly seen in lawns infested with scarabaeid larvae. Its geographic range includes California, Arizona, Texas, Mexico, and Haiti. The head is black, and the thorax is black, with whitish hairs anteriorly, as shown in figure 252. The wings are colorless. The abdomen is rufous, with black markings. The legs are black, but are sparsely clothed with white hairs. These wasps are large and robust, and are about 25 mm long.


Of the approximately 20,000 known species of bees, only about 50% are social insects. These are included in the family Apidae, subfamilies Apinae (honey bees and stingless bees), Bombinae (humble bees), Halictinae (sweat bees), and Xylocopinae (xylocopine bees) (Michener, 1969).

Bees are closely related to wasps, but in bees at least some of the body hairs, particularly those on the thorax, are branched and plumose. The body hairs of wasps are simple and unbranched, and many wasps have relatively little body hair. Bees also differ from wasps in that bees provision their nests with pollen and honey, whereas wasps generally feed their young on meat. [Some masarid wasps (Pseudomasaris spp.) (figure 244) provision their nests with pollen and nectar.]

Honey bees and bumble bees differ from most nonparasitic bees in laying their eggs in unprovisioned cells (figure 253), and even the bumble bees place the eggs of the first generation in a bed of pollen. Nearly all other species of nonparasitic bees bring food to the nest before any eggs are laid. The honey bee and other species of Apis feed their larvae from the time they are hatched until they are ready to pupate (Stephen et al., 1969).

Bees are best known as providers of honey and wax, but they are of much greater importance as pollinators. Their branched and plumose hairs entangle and hold pollen, and this, along with their continual contact with pollenbearing flowers, results in their being particularly efficient pollinators. Pollen is carried in large masses in hair brashes located on the hind legs of most bees and on the ventral side of the abdomen in a family of solitary bees, the Megachilidae. Honey bees and bumble bees carry pollen in moist balls in special pollen baskets on their hind tibiae, and have the first segment of the hind tarsus greatly enlarged and more or less flattened. Eckert and Shaw (1960) compiled a list of the major nectar and pollen plants of the United States, their major distribution as sources of nectar, and the color of the honey produced. Seventy groups (families, genera, or species) of plants were listed.

In the United States, about 50 agricultural crops either depend on honey bees for pollination or are at least somewhat benefited by these insects. Many species of wild bees are also important pollinators.

Unfortunately, bees are also the most important sources of insect stings, the honey bee being the worst offender. Both bees and wasps frequently find their way into moving vehicles, and have caused many accidents. Honey bees can also become pests by locating their nests in attics, chimneys, or in the hollow walls of buildings. The bees themselves may be annoying, and in warm weather or near sources of heat, such as stoves, fireplaces, or furnaces, combs filled with honey may melt and saturate ceiling or wall plaster. The honey may drip through the ceiling plaster to rooms below.

Honey Bee, Apis mellifera L. (Apidae)

Honey bees are not indigenous to North America north of Mexico, but were introduced by early immigrants. Any "wild" honey bee colonies are the progeny of those that have escaped from apiaries and settled in hollow trees and other suitable nesting sites, where they may establish large colonies of 20,000 to 60,000 individuals.

Description. There are 3 castes: the workers, the queen, and the male or drone. Most people see only the worker caste. The workers are 11to 15 mm long, mostly various shades of brown and black, with the head, antennae, legs, and portions of the abdomen dark (figure 254). A dense, short, buff or pale pile clothes most of the body, being thickest on the thorax and thinnest on the dorsum of the abdomen. The queens are large, and 15 to 20 mm long. The queen's pointed abdomen extends a considerable distance beyond the tips of ttie wings. The drones are robust, and 15 to 17 mm long. A particularly significant anatomical feature of bees is the elongate "tongue" formed by the maxillae and labium. The tongue enables bees to reach the nectar in flowers that have moderately deep corollas.

Biology. The queen may live as long as five years. She can lay as many as 1,500 to 2,000 eggs a day, placing 1 egg in each cell of the brood comb. However, queens are seldom profitable after the second year, and most beekeepers believe it is profitable to "requeen" yearly (Root and Root, 1935). The queen bee produces many pheromones, mostly in her mandibular glands. The pheromones include the "queen substance" (trans 9-keto-2-decenoic acid), which can be made synthetically. It is passed from worker to worker orally. Among its functions is the inhibition of the development of ovaries in worker bees. Its absence induces the workers to construct new queen cells. When the concentration of queen substance in the hive falls below a certain level, new queens are produced. This pheromone is also a sex attractant for drones in the mating flight (Blum, 1970).

The workers are abortive or neuter females that arise from fertile eggs. Their reproductive organs are incompletely developed. The young workers take care of the young brood, build the comb, and protect the entrance to the colony against invaders. Older workers collect pollen, nectar, and propolis. Propolis, sometimes called "bee glue" is a brownish, resinous material of waxy consistency collected from the buds of trees and used as a cement for closing small crevices in the hive. During the summer months, the worker bees live only 6 or 7 weeks, but those hatching in the fall survive the winter, feeding on honey stored up through the summer, and then perform the work of early spring.

The comb consists of 2 layers, back to back, of 6-sided cells constructed of wax. The cells around the top and sides of the comb are for storing honey, and are capped with wax. The lower and central portions of the comb comprise the brood comb. Most of the cells of the brood comb are similar in size to those used for storing honey, but the development of worker bees takes place in most of these uncapped cells. The wax used to construct the comb is secreted in glands on the underside of the abdomen, and is masticated and mixed with cephalic gland fluids. If the colony increases in size to the extent that the founding of a new one becomes necessary, the workers construct special cells for the rearing of queens and males. Males (drones) are reared in larger cells than those of the workers, often located in the lower corners of the comb.

To prepare a cell for rearing a queen, the workers remove the partitions between 3 adjacent cells containing eggs, and destroy 2 of the eggs. The remaining egg hatches, and the larva is fed the highly nutritious royal jelly during its entire larval life. The sequence of events leading to royal jelly is as follows: After nectar is brought back to the hive in the honey stomach of a forager, it is transferred to other workers (hive bees). The latter "ripen" it by forming a droplet beneath their mouthparts and expanding and contracting this droplet, thereby evaporating excess water to about 20% of the total solution. The resulting 80% sugar solution, with small percentages of pollen, is called honey, and is stored in cells as adult food. Later, nurse bees (young adtilt workers) consume pollen and some honey to manufacture royal jelly, and others mix pollen, nectar, and secretions to form worker jelly or bee bread to feed the brood. Several queens may be produced simultaneously within the hive. All other larvae are fed royal jelly for only 3 days, after which they are provided with worker jelly and other food.

The old queen tries to destroy the new virgin queens, but the workers protect them. Then the old queen and a large number of workers leave the hive and "swarm" to seek a suitable place for a new colony. A struggle among the virgin queens then takes place, and only the most vigorous one survives. Ordinarily, this is the only time a queen uses her stinger. Several days later, the surviving queen makes her mating flight. Mating takes place while in flight, and it may be with males from her own hive or any other. The queen mates only once during her life. Egg-laying ordinarily diminishes by the first or second year of the queen's adult life. In any case, the supply of spermatozoa in her spermatheca becomes exhausted, and the eggs are no longer impregnated. Even though she may continue to lay eggs in worker cells, only drones are produced (Root and Root, 1935). After the swarming season sometime during the first warm days of spring, the males are driven from the hive or killed by the workers.

Under ordinary conditions, the developmental period for the worker is 21 days; for the drone, 24 days; and for the queen, 15 or 16 days. About the first half of the worker's life is normally devoted to hive duties, and the last half to field duties. The average life of the worker during the summer is not over 3 months and, over the height of the honey flow, perhaps an average of 5 weeks. If drones were kept in a queenless hive, they might live for 3 or 4 mgnths, but ordinarily their lives are even shorter than those of workers. However, the queen may live several years.

Among the races of Apis mellifera, the Italian race is superior. It is gentle, is the best producer of honey, builds few queen cells, does not run over the comb, keeps out the wax moth (Galleria mellonella), and is the most resistant to European foul brood.

The Language of Bees

One of the most amazing phenomena in biology is the bee dance, a form of communication unique in the animal kingdom. We owe the revelation of the full significance of the bee dance, and of the physical and biological phenomena involved, principally to the ingenuity and perseverance of the great entomologist and Nobel laureate Karl von Frisch and his associates in a series of thorough and painstaking experiments. [Unknown to von Frisch in the early years of his experimentation was the fact that, in 1788, Ernst Spitzner had observed that a scout bee, "full of joy," twirled in circles in the hive and was followed by other bees when she returned to the source of the food, which in Spitzner's experiment was honey (von Frisch, 1967).] A scout bee is able to communicate the location of a food source to other bees in the darkness of the hive and on the vertical plane of the honeycomb. Upon returning from a good source of food, she may perform a round dance if the food is less than 10 m away. She runs rapidly in a small circle on the comb, first in one direction then in the other, followed by other bees which have received the message that food is near-by. If the food is nectar or pollen from flowers, their fragrance will remain on the scout and give the other bees a clue to the source. If the food source is farther than 100 m from the hive, the scout performs a different kind of dance, called the tail-wagging dance. (Distances between 10 and 100 m are indicated by transitions between the round and tailwagging dances, with a gradually increasing preponderance of the latter with increasing distance.) In the tail-wagging dance, the scout imparts not only the information given in the round dance, but also the direction and distance of the food source. She runs through a short, straight stretch and then returns in a semicircle, alternately to the right and to the left to the starting point, completing a figure 8. On the straight portion of her course, she makes lateral waggling motions of the body-about 13 to 15 waggles per second. The farther away the source of honey, the fewer the cycles of the dance in a given time. The direction of the straight (tail-wagging) part of the dance indicates the direction of the food source, the sun being used as a reference point. If the scout moves upward in the tail-wagging part of her dance, this indicates that the food source is in the direction of the sun; if she moves downward, this indicates that the food source is in the direction opposite to that of the sun. If the tail-wagging stretch of her run is to the left (or right) of vertical, this indicates to the bees following her that the food source is left (or right) of a direct line to the sun. The angle of the line from the vertical indicates the angle from the direction of the sun the bees must take to reach the food source. Since all this activity is taking place in the dark except when observed under glass by the investigator, the bees orient the straight portion of the dance at the same angle to the force of gravity as the angle they have flown with respect to the sun during the flight from hive to the food source (von Frisch, 1950, 1967).

The amount and quality of the food are indicated by the duration and vivacity of the dance, and the soliciting dances last only as long as the food is in abundance. The bees directed to the food source by the original discoverer likewise become messengers via the bee dance, and soon a large portion of the colony is engaged in the exploitation of the newly discovered food source (Lindauer, 1960; von Frisch, 1967).

In their waggle dances, bees indicate a greater distance if the flight to the food source is to be against a head wind than if it is to be in a quiet atmosphere. Also, a shorter distance is indicated if a tail wind is to be encountered (von Frisch, 1948; von Frisch and Lindauer, 1955). The dancers even indicate a longer distance if the flight is to be uphill than if it is to be downhill (Heran and Wanke, 1952). This implies that distance information is based on the amount of energy needed during the flight rather than the flying time (Lindauer, 1960).

The sun is not always in sight as a compass for orientation. It may disappear behind clouds, mountains, or the edge of a crest, but the bees still orient their hivemates with their waggle dances under such conditions. A small patch of blue sky is sufficient to reveal the sun's position to bees, for they are able to recognize the plane of vibration of polarized light that comes to earth through this clear patch of sky. The direction of vibration of polarized light, together with the percentage of light that is polarized, determines the sun's position in the sky. Provided the clouds are not too thick, bees can also determine the position of the sun when the sky is completely overcast, for 5% more ultraviolet light penetrates through clouds directly in front of the sun than elsewhere, and bees are particularly sensitive to ultraviolet light (von Frisch et al., 1960).

Mautz (1971) determined that all bees that had been successful in finding an artificial food source 400 m from the hive were individuals that had followed 5 or more tail-wagging runs of the dancing bee. Those following fewer than 5 runs might not find the food source.

Forager bees can become househunters, and a few days before swarming occurs, they search for a suitable home and impart the distance and direction by the same kind of waggle dance used for informing their hivemates about a food source. In either case, the bees' language can be interpreted by man, who has on a number of occasions obtained the message of the waggle dance and awaited the arrival of the first bees at a new food source or future home. One can readily imagine this to be the "unforgettable experience" described by Lindauer (1967).

Honey Bees on Residential Properties: Outdoors

Honey bees may form a "colony"or "swarm" on the limb of a tree or in a shrub (figure 255) on a residential property. This happens when a queen becomes tired and settles on a place to rest. The location where she settles is not necessarily suitable for a permanent colony. In that case, scout bees seek a suitable location, and the colony will follow the scout that gives the most enthusiastic "dance" to indicate the discovery of a suitable location for a permanent colony. If the homeowner will wait 3 or 4 days, the bees will usually leave of their own accord. In the meantime, it is desirable to cover chimney openings or any hole leading to an attic, wall void, or other enclosed place that may be found by the bee scouts. However, in areas of prolonged dry seasons, as in the Southwest, if the co!ony happens to become established under a dense canopy of foliage (figure 255) or in a thicket, the bees may remain there until the first rains of late fall or winter before moving on to a better location. If a garden sprinkler is set so that it allows a "rain" to fall on the colony, the bees may move immediately. A strong stream of water can dislodge bees, but will infuriate them and cause them to sting.

Sometimes, beekeepers are willing to come and pick up bee colonies. But in the Los Angeles area, the experience has been that those beekeepers who have left their telephone numbers at fire stations or other appropriate public places for the benefit of persons who wish to have bee colonies removed from their premises soon ask to have their names removed because of the overwhelming number of such requests.

One can get rid of bees that have colonized on a tree. shrub, under the eaves of the house, or in some other suitable location, by the use of insecticides. Using a "hose-attachment" garden sprayer and a thin stream of spray, the colony can be treated from a safe distance with potent insecticides such as dichlorvos or lindane. The cluster of, bees should be completely covered with spray. The person applying it should then run into the house. By the next morning, the bees should all be dead or gone, despite the fact that many may not have been wet by the spray.

Most people are reluctant to kill bees or to ask pest control operators to do so because bees are thought to be beneficial as pollinators. A simple and effective way of removing a colony hanging free on a limb is to place beneath it an open cardboard box with the cover flaps bent outward. The box should have a slot about 5 in. (13 cm) long and 2 in. (5 cm) wide cut out of one side near the bottom in such a way that the part cut out can be bent down to form a runway for the bees. (The reason for the slot near the bottom of the box is to encourage the bees to use it instead of the top.) Then, strike the top of the limb with a pole, which will cause the bees to fall into the box. The limb should be tapped until all the bees have fallen. This will not arouse their anger, for they prefer to have their colony in an enclosed space, and will be "glad" to find themselves in the more suitable location. The best time to do this is during the warmest period of the day, for the bees are then at their peak of activity and are therefore the most gentle. Although homeowners have done this without previous experience, it is probably prudent to get someone with more experience or with protective clothing and a bee veil to do the job, for it is possible that a person could be stung, and the reactions of some individuals to bee stings are very severe. Later, the flaps on top of the box can be closed, using a long pole, and a board placed across the top. All motions should be slow and deliberate, and it is helpful to wear clean, white clothes, free of perspiration. At night, when the bees' activity in leaving and entering the box has practically ceased, the flaps and the slot near the bottom can be sealed with masking tape. The colony can then be taken away and released in some appropriate area.

The rule for safety in the presence of bees is slow, deliberate movement. By observing this rule, it is possible to open the hive and even tear the comb to bits.

Honey bee colonies situated in the sun are said to be "good-natured," while those in dense shade are usually the reverse. Bees are generally very gentle in the middle of the day when the air is warm and they are going out into the field. If a sudden rainstorm develops, shutting off their supply of nectar, they will usually become quite irritable, and this "bad temper" will last until the normal supply of nectar is again available. Bees will become "angry" f one offers them a bit of food, such as honey, and then suddenly withdraws it. They are also likely to be belligerent toward nightfall on chilly days. Root and Root (1935) stated: "When all are at home, and the hives are opened unceremoniously, they may resent the intrusion. It is then that beginners discover, much to their sorrow, that bees should not be handled during cool or chilly weather, right after a rain, or at night."

Bees never injure sound fruit, no matter how soft and juicy it is or how thin the skin. Even fruits such as grapes, peaches, and apricots that were placed in hives of bees that had been purposely starved were not molested (Root and Root, 1935). If they are seen sipping fruit juice, it is an indication that the skin or peel has been broken by some other marauder, such as a yellowjacket or a bird.

Honey Bees on Residential Properties: Inside a Structure

If bees colonize in the attic (figure 256) or wall voids of a house, they present a potentially serious problem. The wise procedure is to get rid of them as soon as possible. Large quantities of honey can be produced within a few months, and the combs and honey can melt and seep through plaster, particularly near a kitchen stove, furnace, or firepllace. The odors of dead brood and rancid honey are other adverse results if removal of the bees is delayed too long (Pence, 1955). During warm weather, the hive is constantly cooled by the fanning of thousands of wings. If the colony is destroyed, the cooling process ends and the wax combs may melt, releasing the honey. Bees also remove excessive moisture, and when this process stops, the honey may burst the wax cappings and , rain into the wall.spaces. If the bees are killed, ants, wax moths, carpet beetles, soldier flies, and cockroaches may find their way to the comb to feed and breed.

In one way, infestation by wax moths (Galleria mellonella) after the bees are gone can be beneficial, for their larvae can eventually clear away the old combs in wall voids and discourage further occupancy by bees. On the other hand, if combs containing honey are dislodged and fall to a fire block or floor plate, the honey may soak through plaster, wallpaper, or wood interstices and cause damage. Wax moth larvae will sometimes move to the edges of the comb area and gnaw out oval depressions in which to pupate. If they crawl through a crack or opening in the wall plaster and pupate beneath the wallpaper, a lump beneath the paper may result (Happ, 1966).

If Argentine ants find an inaccessible hive, their trails may be found leading to points of entry into the wall void, chimney, or other closed space where the hive is located. The ants can be allowed to remove the store of honey, but extra care must be exercised to avoid leaving any exposed sweet material in the living space of the house that will attract their foraging scouts.

Control with Insecticides

Nearly any insecticide sprayed or blown into an enclosed space such as a wall void will kill bees, particularly when applied as a dust, which enetrates well. With a volatile insecticide, such as dichlorvos or lindane (particularly the former), one can use a hose-attachment sprayer and with a thin stream sometimes reach the bees' entrance hole from the ground. With such volatilizing insecticides, a large quantity and thorough coverage of the comb are unnecessary. A 5% chlordane or carbaryl (Sevin®) dust is commonly used. Dusts can easily be applied with a plunger-type garden duster with the baffle removed, using about 0.5 Ib (0.23 kg) of dust per colony. Among toxic insecticides, carbaryl dust appears to have an important advantage in addition to its efficacy in killing bees when exterminating them in wall voids and attics. It kills the bees slowly, and they tend to leave the building before they die. The odor resulting from dead bees is avoided.

One can also drop small pieces of dichlorvos "resin strip" into a bee-infested cavity. This, as well as dusting and most types of spraying, requires that a person climb up to the hole to introduce the insecticide. This should be done at night when there is minimal traffic in and out of the entrance hole. Generally after the colony has been treated, one side of the double wall must be taken down and the comb and honey removed.

One pest control operator set up a chlordane fogger outside ahouse to prevent bees from attacking him while he drilled 2 holes in the siding. He inserted 2 plastic void-injector tubes in the holes and attached the tubes to 3-Ib (1.36-kg) pyrethrin aerosol bombs to kill the beft. When the siding was removed, he found the combs were as wide as 18 in. (45 cm) (the distance between 2 studs) and as long as 7 ft (over 2 m). He removed the combs and honey, cleaned the studs, applied 2% chlordane spray to the infested area, and replaced the siding (Goforth, 1964). A particularly useful device for dispensing aerosols in the control of bees, as well as wasps, is the Hi-Spray Aerosol Dispenser [Product of Ashcombe Products Company, Route 5, Box 75, Dover, Pennsylvania 17315.], on which the canister is mounted at the end of a pole. With this equipment, one can reach a distance of 13 ft (4 m) without an extension and 18 ft (5.5 m) with an extension pole. The aerosol is activated by pressing a button inside the base of the handle. The equipment weighs less than 3 Ib (1.36 kg) with the can.

Removal of a Living Colony

Even when bees have located their colony within a wall void, many people are reluctant to destroy them. A method of removing them from a wall void has been devised which does not require killing the bees, and in fact after they have been relocated outside the house, they will remove the honey from the wall void. Building repairs are avoided and a useful colony of bees is made available. The job can be done best by an experienced beekeeper, although pest control operators and even the homeowner may be tempted to try, with the aid of an illustration and a description of the simple procedure. The instructions are copied verbatim from Stanger(1967):

Fold a piece of window screen to make a cone 18 in. [45 cm] long and wide enough at the bottom to cover completely the entrance used by the bees. Bend the cone slightly upward toward the smaller opening, which should be about 0.5 in. [12 mm] in diameter (figure 257).

Protect yourself with a bee veil and use a bee smoker to smoke the bees' entrance to the building. Then tack the screen cone tightly over the entrance.

Plug all other holes where the bees may re-enter the building.

Near the entrance, place a 1-story hive containing a queen bee, I frame of unsealed brood covered with bees from an established colony, and new frames. (A frame with brood and a queen can be obtained from a bee supply house or local beekeeper. It can be ordered by mail from the bee supply house.) The hive may be on a separate stand or on brackets nailed to the building (figure 257).

The bees will emerge from the screen cone and fly to the outside, but will be unable to find their way back into the old nest through the opening in the cone. Instead, they will enter and become established in the new hive, near their old entrance. As the bees move out ot tne building into the hive, the old colony will grow weaker and be unable to maintain itself in the building. In about 4 weeks, remove the screen from the entrance. The bees in the hive will enter the old nest and transfer the honey to the new hive. When the bees have moved from the building, close all holes and cracks to prevent another swarm from entering.

The African or Brazilian Bee

The African bee is a yellow strain of the subspecies Apis mellifera adonsonii Latreille, said by some observers to be slightly smaller than the common honey bee of the United States, but otherwise indistinguishable by casual observation. Two dozen swarms of this strain of bees were inadvertently permitted to escape into Brazil in 1956, and have subsequently multiplied rapidly and lare reported to have spread over most of Brazil and into Paraguay, Uruguay, Argentina, and Peru. Some investigators believe that they are now moving northward at the rate of about 200 mi (320 km) a year, and could reach the United States in 10 years, or sooner if accidentally introduced. The mixture of the African bee with the European bees of Brazil has resulted in a strain that can appropriately be called the "Brazilian bee." Some investigators have reported the Brazilian bee to have a much different behavior than the European bees of the United States, mainly the German race, Apis mellifera mellifera L., among the wild bees and mainly the Italian race, Apis mellifera ligustica Spinola, in the apiaries. They state that the sting of the African bee is no more painful than that of the bees of the United States, but that it is more aggressive and stings more readily. They report a common belief that Brazilian bees swarm and migrate oftener, that the queen lays more eggs per day than the queen of the United States bee, and that as the Brazilian bees invade an area they replace other bees (McGregor, 1970; Gary, 1971).

The initial apprehension concerning the Brazilian bee is now subsiding. Most of the adverse claims concerning ihe Brazilian bee could not be verified by the Committee on the African Honey Bee, consisting of 9 members from the United States, Canada, and Mexico under the auspices of the Division of Biology and Agriculture, National Research Council, National Academy of Sciences, Washington, D.C. In the early 1970's, the African bee was introduced into Poland and built up to 30 colonies. These bees were reported to be more aggressive than the local ones, but no more so than a race (A. m. silvarum) from northeast Poland. The African bees did not swarm, and their honey production did not differ from that of domestic colonies. These bees did not spread and become a problem throughout Europe. Also, African bee semen was used to inseminate queens of domestic bees through 3 generations at Baton Rouge, Louisiana, to produce a strain over 90% African, but the resultant offspring presented no special problems. In any case, colonies with aggressive bees can easily be requeened to change their temperament (Cantwell, 1974).

In southern Brazil, where European bees were kept in considerable numbers before the arrival of the Brazilian bee, the new race of honey bees is gentler than it is in northern Brazil. Presumably, there has been a dilution of African traits through interbreeding. Also, beekeepers have selected for gentler colonies. The new Brazilian strain is reported to be producing more honey per colony than the Italian bee under the same circumstances, an d beekeepers in southern Brazil have learned to handle the new race and to take advantage of its productivity.

The large number of European honey bees now in Mexico may considerably dilute the characteristics of the bees now in northern Brazil, and the strain that eventually reaches the United States may be considerably different from the one now spreading northward in Brazil (Michener, 1973).

Bumble Bees, Bombus spp. (Apidae)

Bumble bees are almost world-wide in distribution, and are found even within the Arctic regions and up to 13,000 ft (about 3,900 m) elevation in temperate regions. Unlike most social insects, they are more numerous in temperate and even in Arctic zones than in the tropics. They occur throughout the United States, but are most abundant in the Sierra Nevada, Cascade, and Rocky mountains and in the northernmost states. All are nestbuilders, and the colony consists of queens, males, and workers. Bumble bees are medium- to large-sized, robust, and densely haired. The hair is usually black, with areas of orange or bright yellow. Queens and workers have pollen baskets on the hind legs. Unlike honey bees, they have terminal spurs on the hind tibiae.

Biology and Habits. Fertilized bumble bee queens must hibernate. Most of them prepare for hibernation by digging a small chamber ot hibernaculum in the soil, frequently near the entrance to the nest in which they were reared. Some hibernate in hollow trees and other protected places. In the spring, they appear and feed on nectar when the early plants bloom. A queen will then seek a suitable nesting place in a clump of dry grass, an old bird nest, a deserted mouse nest aboveground, in a burrow abandoned by a rodent, ox sometimes even in a building. When the nest has been established, she proceeds to build a "honey pot" (figure 258, F, L) from the wax that extrudes from between the sclerites of both dorsal and ventral abdominal surfaces. She fills the honey pot with nectar, and builds a cell, usually from a mixture of wax and pollen, for her eggs. The eggs of the first brood vary in number, from 1 per cell in the subgenus Bombias to as many as 10 or 12. She constructs the cell on top of a mass of paste made of pollen and honey, covers it with a wax cap, and broods over the eggs to incubate them. The larvae hatch in 3 to 5 days, and feed on their bed of pollen-and-honey paste. The queen continues to care for her young. Some queens gnaw a hole in the lid of the cell and supply the larvae with regurgitated honey and pollen, while others push pollen in under the developing brood.

About 3 weeks are required for larval and pupal development, and then the first brood of small workers appears. These gather food and construct brood cells, relieving the queen of all duties except egg-laying. While the colony is in the early stages of development, some of the queen's eggs are never laid, but are reabsorbed. As the number of workers increases, the queen usually lays more eggs. If larvae receive ample food, they become queens, but if partially starved, they become workers (Free and Butler, 1959). A large community of bees eventually occupies the nest, which may attain a diameter of 20 to 30 cm and be lined with straw or other dry plant material. The nest may have several entrances. The upper and mbst recent cells contain brood (figure 258, D, E), whereas the lower cells, from which brood has emerged, contain pollen and honey. In the later broods the workers are larger, some approaching the size of the queen. With the appearance of the new queens, unfertilized (male) eggs are laid. When the males mature, mating takes place. The fertilized queens seek hibernating quarters, and the workers, old queen, and males soon perish.

Bumble bee colonies generally contain a few hundred individuals, although the population of a thriving colony may reach 1 or 2 thousand (Michener and Michener, 1951). There is no strict division of labor within the nest, and the large workers are more inclined to go on foraging trips. These large bees are probably stronger fliers, and can collect larger loads of nectar and pollen (Free and Butler, 1959).

Bumble Bees as Pollinators

Certain kinds of clover seed cannot be grown where bumble bees or other long-tongued bees do not occur. The tubular part of the flower of the red clover, Trifolium pratense, may be as long as 9 to 10 mm (as short as 5 or 6 mm under and conditions), and the tongues of some bumble bees are long enough to enable them to reach the nectar at the bottom of the longest tubes. In doing so, they pollinate the flower, visiting as many as 25 to 35 flowers a minute. In his Origin of Species, Darwin (1859) recorded that 100 heads of red clover visited by bees produced 2,700 seeds,whereas another 100 heads from which bees were excluded produced none. In New Zealand, where the bumble bee is not native, a bumble bee (Bombus terrestris) had to be introduced before red clover began to produce seed. In cool, humid areas, such as parts of Canada and the northern United States, bumble bees and leafcutting bees (Megachile) are more important than honey bees for the pollination of alfalfa (Bohart, 1958). With increasing knowledge of the biology of bumble bees, their colonies might be managed for the pollination of many important crops, particularly legumes (Medler, 1958; Holm, 1966).

Common California Species of Bumble Bees

A taxonomic study of 27 species of bumble bees of western America was made by Stephen (1957). It includes keys to queens, workers,and males, species descriptions, and notes on variations within species, biology, distribution, and flight records. The color patterns of most bumble bees are very variable, particularly for males, and structural characters used by taxonomists are more reliable for identification. However, they would be of little value to the average reader. The following descriptions are brief and nontechnical, adapted mainly from Stephen's work, of some species that are common in California.

Yellowfaced Bumble Bee, Bombus (Pyrobombus) vosnesenskii Radoszkowski

This is the most common species in many parts of California. It ranges throughout the Pacific Coast states from Washington southward, and eastward to western Nevada. Its appearance is remarkably constant throughout its range. The queens are 14 to 19 mm long, the males 10 to 14 mm, and the workers 9 to 14 mm. The color is black, except for the face, occiput, pronotum, and mesonotum in front of the wings, and the dorsum (tergite) of the fourth abdominal segment, which are yellow.

Bombus (Pyrobombus) caliginosus (Frison)

This species is found in coastal regions of the Pacific Northwest, and in California as far south as the San Jacinto Mountains. It closely resembles the foregoing species, and it is hard to distinguish the workers and queens of the two; their color patterns are almost identical. The male genitalia offer the only certain characters for determination.

Van Dyke's bumble bee, Bombus (Pyrobombus) vandykei (Frison)

This bumble bee ranges throughout the Pacific Coast states, and appears to be most closely related to B. caliginosus. The females of B. vandykei from southern Oregon and California resemble those of B. caliginosus superficially, but in caliginosus the third abdominal tergum has black hairs and the fourth has mostly yellow hairs, while in vandykei the third abdominal tergum has yellow hairs apically and the fourth has black hairs. Bombus vandykei has been most abundant in collections from the transverse mountain ranges of southern California and along the western foothills of the Sierra Nevada below 6,000 ft (1,800 m) elevation, but is uncommon in coastal areas where B. caliginosus occurs (Thorp, 1969).

Edwards' bumble bee, Bombus (Pyrobombus) edwardsii Cresson

These are relatively small bumble bees, the queens ranging from 15 to 17 mm long and the workers, I I to 12 mm. The queen has 2 yellow stripes on the thorax, separated by a wide, median, transverse band of black between the bases of the wings. The yellow pile comes down the side of the thorax and covers the area from legs to wings. It is a less intense yellow color than in the preceding species. There is also yellow pile on the face, as well as yellow bands on the first, fourth, and fifth abdominal tergites. The workers have the same general yellow-black pattern as the queens.

Bombus (Protobombus) bifarius bifarius Cresson

and B. (P.) b. nearcticus Handlirsch
Bornbus bifarius bifarius and B. b. nearcticus are common and highly variable species, found from Alaska to California and southern Utah and from sea level to 10,500 ft (3,200 m) elevation. Their range does not extend as far south as southern California. Bombus b. nearcticus is by far the more abundant of the 2 subspecies, being found in great numbers throughout eastern Washington, Oregon, and in the mountains of northern California. Both subspecies have the first and fourth abdominal tergum yellow and the fifth and sixth black. Bornbus b. bifarius has redorange pile predominating on the third abdominal tergum and traces of it on the second. Bombus b. nearcticus has a small amount of orange-red pile only on the third tergum. There is an intergradation between the two.

California or Blackfaced bumble bee, Bombus (Fervidobombus) californicus Smith

This species ranges from the eastern slopes of the Rocky Mountains to the Pacific and from British Columbia to Baja California. The queens are 20 to 24 mm long, and have yellow pile on the anterior half of the thorax and a single yellow stripe across the fourth abdominal segment. The workers have the same general yellow markings. They vary greatly in length, from 12 to 22 mm. Neither queens nor workers have yellow pile on the head. This species has been confused with B. vosnesenskii, but has black pile on the face.

Sonora bumble bee, Bombus (Fervidobombus) sonorus Say

This species is one of the larger bumble bees of western America. It appears to be the most common one in southern California. The queen is about 30 mm long, and has yellow pile on the thorax, but usually has a black dividing band across the thorax from wing to wing (figure 259), and the sides are black. The first 3 abdominal tergites have yellow pile. The workers are much smaller (15 to 20 mm), but have a similar color pattern. Throughout the range of the species in western America may be found specimens with the dorsum of the thorax almost or completely covered with yellow pile.

On the UCLA campus, B. sonorus had a nest in the ground at the base of a high fence heavily covered with ivy. The author was stung on the head on 2 occasions while walking alongside the fence, but the workers are normally more likely to merely threaten an intruder by fast, circular, vertical flights in the region of the head and shoulders. Protective clothing was used when digging up the nest in 1971, and nearly all the bees were captured. There were about 450 bees in the colony.

western bumble bee, Bombus (Bombus) occidentalis (Greene)

This species occurs along the eastern slopes and plains of the Rocky Mountains, westward to the Pacific Ocean, and northward into Canada and Alaska. The queens are 15 to 18 mm long, the males 11.5 to 15.5 mm, and the workers 9.5 to 15 mm. In the Rocky Mountain form, the face has yellow pile mixed with black; the anterior dorsum of the thorax is yellow; a broad black band appears between the bases of the wings; the scutellum, has yellow and black pile; the legs are black, the tarsi brown, and the pollen basket is rusty red-brown. The abdomen is always black at the base, yellow on the dorsum (tergite) of the third segment, and whitish-ferruginous at the posterior 2 segments. The workers and queens are similarly colored, but the males have more yellow and whitish ile. In northern California, B. occidentalis has predominantly black hair, with yellow and black intermixed in the face, yellow on the thorax in front of the wings only, and white on the terminal 2 segments (fifth and sixth), and often the apex of the fourth tergum. This form grades into the one in the San Francisco Bay area (subsp. nigroscutatus), in which the terminal white becomes buff, with yellow on the third tergite and apicolaterally on the second tergum.

Crotch's bumble bee, Bombus (Crotchiibombus) crotchii crotchii Cresson

This large and rather striking species occurs in California and northern Mexico. Three queens measured were 23 and 24 mm long, and 4 workers were 14 to 18 mm long. There is little difference in appearance between queens and workers. These bees have a little yellow pile on the head and a yellowish golden pile on the anterior half of the thorax. The abdomen is black, except that the wide second abdominal tergite is yellow, and segments 4, 5, and 6 may have much brick-red or rusty red-brown pile. The yellow shades on B. c. crotchii vary from light to bright yellow.

Morrison's bumble bee, Bombus (Separatobombus) morrisoni Cresson

This species is almost entirely distributed east of the Cascade-Sierra chain of mountains, becoming rather common in southern Idaho and Utah and one of the most common species in New Mexico and Arizona. In the workers, almost the entire dorsal surface is covered with bright-yellow pile, only the terminal part of the abdomen being black (figure 260). In the queen, the yellow pile does not extend so far posteriorly as in the workers. The yellow is paler in the north and at higher altitudes. In California, this species occurs only east of the Sierra and apparently not south of Whitney Portal in Inyo County.

Control of Bumble Bees

Bumble bees can be destroyed by spraying or dusting an insecticide into their nests, as for the control of honey bees and wasps.

Cuckoo Bumble Bees

Cuckoo bumble bees (Psithyrus) are inquilines in one of the accepted definitions: "Any animal living habitually in the nest or burrow of another animal" (Pennak, 1964). They closely resemble Bombus spp. except that they do not have pollen baskets on the hind legs. They live as inquilines or uninvited guests in the nests of true bumble bees. The females may be seen in the spring a few weeks after the queen bumble bees appear, and they lay eggs in the nests of the latter. If not promptly ejected or killed, they become accepted into the bumble bee colonies. Psithyrus has no worker caste, and the young are fed and cared for by the bumble bee workers. According to Free and Butler (1959): "It is perhaps significant that when a Psithyrus female first enters a nest, she often hides under a comb or nesting material for some time, for by so doing she may, in fact, be acquiring an odor similar to that of the colony's inhabitants." The cuticle of Psithyrus is thicker and tougher than that of Bombus, and her stinger is longer. She is a formidable adversary when fighting is required, and in one nest, the bodies of no fewer than 20 Bombus queens were found after such a battle. There are some exceptions, but the cuckoo bumble bee in most cases strongly resembles her principal host species in color and markings.

There are 2 species of Psithyrus presently recorded for California: P. crawfordi Franklin and P. fernaldae wheeleri Bequaert and Plath. Both species are represented in California by color forms that mimic B. vos ble bees of this color pattern, especially B. caliginosus, B. vandykei (var.), and B. californicus. The females of both species of Psithyrus are predominantly black, with yellow hair on the vertex, the thoracic dorsum in front of the wings, and the fourth abdominal tergite. In addition, P. crawfordi has yellow on the face above and sometimes below the antennal bases and laterally on the fifth tergite. Another staking difference is that P. fernaldae has the tip of the abdomen strongly recurved beneath, with the last sternite projecting beyond the apex of the last tergite (R. W. Thorp, correspondence).


As stated at the beginning of this section, about 95% of the bees are solitary in habit. The female prepares her own nest, provisions the cells of her nest with nectar and pollen, oviposits, but manifests no further interest in the welfare of her offspring and survives for only a single season. The solitary bees are rather closely related to the sphecoid wasps and have similar nesting habits, except that they provision their cells with pollen and honey instead of meat. Unlike honey bees and bumble bees, solitary bees do not have, pollen baskets on the hind tibiae. Pollen is carried on pollen brushes on the legs or abdomen (Eckert and Shaw, 1960).

The number of solitary bee species is particularly great in the warm, arid, or semiarid deserts of the world, such as in the southwestern United States. Here there are species that fly in the spring and obtain nectar and pollen from herbaceous mesophytes (plants that exist under medium conditions of moisture) that grow and bloom during the brief period when the desert is relatively moist. Other species depend on xerophytes (plants structurally adapted to resist drought) that bloom not only in the spring, but also later in the year. Even entire genera tend to fall into one or the other of these categories. An abundant solitary bee fauna may also be found in mountainous areas with moderate rainfall, varied floras, and well-drained soils favorable for nesting. Agriculture may be beneficial to native bee species that are preadapted to make use of its cultivated flowers, such as cucurbits and alfalfa, but many agricultural practices have reduced the ranges of some native species by destroying their nesting sites, for most of them are ground-nesters (Linsley, 1958).

Some species of solitary bees are important pollinators, at least of certain crops. They have stingers, and sometimes sting people, but the reaction to the stings of most species is mild in comparison with the usual one to the stings of social bees, except in rare cases of specific allergies. One exception is the extremely painful sting of certain solitary bees of the genus Eulaema, which are the size of bumble bees but do not occur in the United States (Stephen et al., 1969).

Family Megachilidae

This family includes the leafcutter bees (Megachile), mason bees (Osmia), and their allies. They are medium-sized, and are usually black, brown, or metallic green or blue in color. The nonparasitic females of the megachilids can be identified by their pollen-collecting hairs (scopae) being located only on the ventral surface of the abdomen (Hurd and Michener, 1955). In other pollen-collecting bees, such hairs are largely on the hind legs or, in a few species, on both the legs and the ventral surface of the abdomen.

Most of the species of leafcutter bees in North America are about the size of the honey bee. To build nests, some females cut out tunnels in rotten or solid wood or in the ground, but most use the hollow stem of a plant, and line the bottom and sides of the nest with circular or oblong pieces of leaves that they have cut neatly and with geometric precision (figure 261). The female then places a paste of pollen and honey in the nest, and lays an egg. This is the first of what is usually a series of cells that are separated by leaf disks (figures 261 and 262). The female of a common southern California species, Megachile davidsoni Cockerell, and her work are shown in figure 261.

The circular leaf disks which this solitary bee had cut from plants were neatly packed into the tube to form a series of cells. The rounded base of each cell was inserted into the concavity of the cell below.

The mason bees (Osmia) are medium-sized, robust bees, and have a uniformly dark, metallic (rarely black) color. The females construct their nests of sand, clay, or soil, bound together with a glutinous substance, in any available cavity, such as "old snail shells, old galls, the keyholes of doors, apertures in wood, stems, or mortar, or under stones" (Matheson, 1951). Some species build their nests on surfaces, as on a wall or a rock, build a cell (figure 262, C) in which to oviposit, and cover the cell with a mixture of clay and saliva. Except for the fact that they substitute clay for leaves, the habits of mason bees are similar to those of leafcutter bees.

Family Colletidae

This is a family of ancient origin, from which all other bees could have been derived. Colletes spp. are moderate-sized bees, with an entirely black integument and usually with well-defined hair bands. They are ground-nesters, forming transparent, cellophanelike, broad cells (figure 263, E), which Torchio (1965) believed could be appropriately called "cocoons." They are formed from a clear, filamentous, gelatinous material secreted by the Malpighian tubules and excreted through the anus. Species of Hylaeus are so distinct from other North American bees that they are easily distinguished. The body is jet black and nearly naked, but has light yellow maculations in nearly all species. The face is triangular, with a long clypeus (Stephen et al., 1969).

Family Halictidae

The halictids are called "miner bees." They are small to medium-sized bees, mostly black, but some with a metallic blue, green, brazen, or cupreous iridescence. A few are mostly or partially red or yellow. Some are communal, in that a few bees work together to dig out an underground tunnel (figure 263, A, E, H). However, each female then digs a short lateral tunnel, into which she brings pollen and nectar before ovipositing. Often, many bees nest close together and use a common passageway to the outside. The nests are frequently made in banks along washes or ravines. Other species are semi-social or primitively social.

The alkali bee, Nomia melanderi Cockerell, is the most important pollinator of alfalfa in the Pacific Northwest, where it can be distinguished from all other bees by the iridescent, yellow, integumental bands present on the abdominal tergites of both sexes (Stephen et al., 1969). Batra (1970) investigated the behavior of the alkali bee in burrow and cell construction, provisioning, oviposition, and larval development by observing 23 nests in 3 glass-sided chambers. Females, beginning between 3 and 6 p.m., excavated their vertical main burrows, 30 to 40 cm long, by midnight, and the lateral burrows by morning. The burrows we're about twice as long as they would be in the harder soils of natural environments. The lateral burrows terminated in cells that were made during the second or subsequent nights at irregular intervals. They were lined with a waterproof oral secretion. The cells were provisioned, usually the following morning, with pollen balls containing 8 to 10 loads of pollen, the first 3 or 4 levels being mixed with nectar. The bee then laid an egg on the pollen ball and closed the cell opening with earth. Eggs hatched in 3 or 4 days, the larva consumed the pollen ball within 5 to 7 days, and the prepupa was formed within I I to 13 days, compared with 10 to 12 days in the field.

The sweat bees (Halictus) are small insects that are sometimes bothersome because they are attracted to perspiration in attempting to obtain moisture. Occasionally, a mild sting may result when attempts are made to brush them away. Even more frequently encountered are tiny bees belonging to the genus Dialictus.

Family Andrenidae

The andrenids are sometimes called "mining" or "burrower" bees. They are always somewhat flattened dorsoventrally, and have an oval rather than a parallel-sided abdomen (Stephen et al., 1969). These are small bees, mostly metallic black, but some are reddish or brownish, and all have a dense pubescence on the head and thorax. The females construct their own burrows and cells in the ground (figure 263, B, C, D) and provision them with nectar and pollen. Both sexes overwinter in the nests and emerge in the spring.

Family Nomadidae (Cuckoo Bees)

The cuckoo bees are small (10 to 14 mm long), wholly or partially black or reddish, or bright, m etallic blue or green, marked with yellow. They resemble wasps in having a wasplike color pattern and sparse pubescence. Most species carry the abdomen in a high or arched position, hold the wings low, and tip the face upward, although these characteristics cannot always be seen on pinned specimens (Stephen et al., 1969).

The cuckoo bees are inquilines in the nests of other bees, often those of the andrenids. In the spring, the females lay eggs in the provisioned nests of their hosts. They lurk about the nest of the host and slip in while she is out foraging for pollen and nectar. The larva of the cuckoo bee is the first to hatch, feeds more rapidly then the host, and may cause the latter to starve, but sometimes there is enough food for both. The inq.uiline larvae may consume their host's eggs or its larvae.

Cuckoo bees are considered to be harmful because they can destroy pollinating bee species.

Family Anthophoridae

The anthophorids comprise a large family of bees that are intermediate in size between the honey bees and the bumble bees, often black, yellowish brown, or gray, and with thick pile. They nest in burrows in the ground, in banks or. in the case of carpenter bees, in galleries made i'n wood timbers, provisioning their cells with nectar and pollen. The cells are lined with a thin wax or varnishlike substance.

Carpenter Bees. Formerly considered to be in the family Apidae, the carpenter bees are now regarded as a subfamily of Anthophoridae (Hurd and Moure, 1963). These bees are discussed more fully in chapter 5, because their role as pests, though rather limited, is in connection with their nestbuilding in wooden structures.They merit brief mention at this point principally because they are so easily confused with bumble bees, having the large, robust appearance of the latter. However, except for the males of certain species, they generally do not have the yellow markings on otherwise black bodies that are so characteristic of the bumble bees.

Carpenter bees do not have the pollen baskets of honey bees, but the posterior tibiae and basitarsi are covered with a dense mass of long, simple or branched hairs that are similar to those of other Anthophoridae. Some carpenter bees are said to be efficient alfalfa pollinators (Bohart, 1958). The females have stingers, but will not use them, even around their nests, unless they are handled or accidentally collide with a person.

The Stinger of the Hymenoptera

In some of the stinging Hymenoptera, the tubular ovipositor has lost its original function and has become a stinging apparatus, 'or stinger." This is called the "sting" in most entomological literature, but it seems logical to use a term for the stinging apparatus that is different from the verb or the term used for the. effect produced. The stinger is situated at the tip of the abdomen, and is withdrawn into the body when not in use. It can be used to identify the females, for males do not sting. The stinger consists of 3 parts; the piercing apparatus, the lateral plate and appendages, and the venom sac and glands, comprising a "hypodermic syringe" type of mechanism.

There are Hymenoptera that bite and others that sting. Among the stinging or aculeate Hymenoptera, there are those that sting to paralyze their insect or other prey so that it may be easily transported to the nest and will not "spoil" while the larva is devouring the nonvital parts. Other species sting their prey in order to kill it, and their stinging apparatus is more complex. A combination of acid and alkaline fluids, each from a separate gland, forms the lethal venom.

The Stinger of the Honey Bee

In the honey bee, the stinger is in a chamber at the end of the abdomen, and only the tapering, sharp-pointed shaft protrudes (figure 264, A). The shaft is composed of 3 parts, the one above termed the stylet and the two below, the lancets. The lancets are held firmly in place, but can slide freely back and forth. The stylet and lancets form a channel, the venom canal, leading from the bulb to the tip of the shaft. The lancets each have a series of 9 or 10 recurved barbs. At D and E of the figure, the stinger is shown in positions of repose and protraction, respectively. To insert its stinger into the victim, the worker bee bends its abdomen downward and inserts the tip of its outthrust shaft with a sudden jab. The lancets are alternately thrust deeper and deeper into the flesh, an action made possible by the recurved points (barbs) along their sides, which keep them from slipping back (Snodgrass, 1949, 1956). A honey bee can withdraw its stinger from an insect, but in the human skin, the lancets become so firmly anchored by their barbs that they cannot be withdrawn (figure 264, B). The bee gets away, but the entire stinging apparatus is left in the skin, as shown in figure 254, and the injured bee soon dies. Reflexaction of the stinging apparatus drives the lancets ever deeper into the flesh, and venom continues to be driven out of the sac.

As shown in figure 264, F, the acid issues from the gland labeled PsnGId and the alkaline part from the gland labeled BGld. The mixture of acid and alkaline fluids is a potent venom used in the combat of queen bees or the defense of the hive by workers. A similar venom apparatus enables the predatory Hymenoptera to kill their prey. The queen has a longer stinger than the worker. Her venom glands are well developed, and the venom sac is very large, but the lancets have fewer and smaller barbs. A queen rarely uses her stinger, even under the greatest provocation, except to attack rival queens.

Before a bee can sting, it must first take a firm hold with its claws. An experienced person is often able to feel this, and can brush the bee off before its stinger penetrates the skin. If it has already been inserted, it should be quickly scraped off with a fingernail or knife. No attempt should be made to pick it off with the fingers, for this will result in squeezing the venom sac, causing the venom to be injected into the wound. If itching and swelling result, one should not rub the affected area, for this will only cause increased pain and swelling. Application of cold cloths or ice packs (mentioned farther on) is recommended.

The Stinger of the Bumble Bee

The stinger of the bumble bee does not remain in the flesh of a vertebrate as does that of the honey bee. The female bumble bee can use her stinger repeatedly and effectively. She may be aggressive in defense of the nest, but most species soon cease to attack. Away from the nest, the female is tolerant and timid. Only 1 victim in 120 cases of Hymenoptera stings studied by Mueller (1959b) was stung by a bumble bee. Bumble bee attacks are most likely to occur if a person inadvertently steps on a nest. The species of the subgenus Fervidobombus, as well as the species Bombus crotchii, are said to be somewhat more persistent in their attacks than other California bumble bees.

Two days after being stung twice by Bombus sonorus, the author was again stung 6 times on exposed areas on an arm ana a leg while attempting to find a nest, using a bee suit for protection. Within a half hour, a swollen, red area 4 to 5 cm in diameter had developed around each dark-red spot that indicated a point of entry of a stinger. By evening, the swollen areas had become very sensitive to pressure, and fatigue and loss of appetite appeared to be associated with the envenomation. By morning, the red areas had spread even farther, but the swelling and sensitivity to pressure had largely subsided. The shoulder muscles of the arm that had been stung twice in the forearm area were slightly sore when exerted. A colleague, stung on the ankle for the first time, reported increasing swelling over a 2-day period; his ankle finally became very badly swollen and itched severely. Two weeks earlier, the author had been stung about a dozen times by yellowjackets (Vespula pensylvanica and V. atropilosa) over a 5-day period, suffering only minor reactions atter the sharp initial pain. The colleague just mentioned had likewise received multiple stings of yellowjackets and hornets during the precedinlr months, but their effects were relatively rnila compared with the sting of Bombus sonorus.


Since wasps and bees are responsible for about 75% of the deaths that occur each year in the United States from arthropod envenomations, it may be appropriate at this point to quote from the classification by Fluno (1961) of 3 types of reactions of differing severity resulting from stings of these insects. These are named "hymenopterism" from the order Hymenoptera, to which ants, wasps, and bees belong.

Hymenopterism vulgaris. In the majority of instances, the effects of a wasp sting are painful, but no serious or lethal, except when the driver of a vehicle loses control in sudden panic. Actual pain felt varies with the individual victim and with the genus or species of wasp, but generally an intense, immediate pain is felt at the site of the wound. Localized reddening and swelling also almost always occur. Depending upon the site affected, there may be interference with normal function; for example, a sting at a finger joint often results in stiffness, with consequent impairment of movement. The pain, swelling, and stiffness may last for only a few minutes or for 1 or more days.

Hymenopterism intermedia. In this arbitrarily classified type of reaction, swelling includes considerable tissue beyond the actual site of the sting, for example, an entire arm or leg. This intermediate reaction may last for several days, but it is not necessarily lethal. However, in this category should be placed cases in which the site of the sting is the tongue, neck, or throat, with occasional involvement of the glottis and consequent impairment of swallowing and breathing.

Hymenopterism ultima. This is the lethal or near- lethal reaction, quickly diagnosed by the alert physician as anaphylactic shock. Generally, the patient goes into shock within 10 to 20 minutes after receiving the sting. Hives may be present, breathing is shallow, pulse and heartbeat are almost undetectable. Profuse sweating generally occurs, and the patient becomes unconscious and obviously in need of medical assistance.

Of the 3 types of hymenopterism, "vulgaris" type seldom prompts the victim to consult a physician, and then only for relief from pain. He may be reacting to only a part of the venom. The victim with an "intermedia" type may be reacting to more of the venom components (enzymatic materials, proteins and proteinlike materials, histamine, 1 or more spreading constituents, and possibly other compounds). Many persons with the intermedia-type reactions do not consult a physician, but they should, for their sensitivity is indicated. Sometime in the future, and possibly with the very next sting, such a person is likely to demonstrate hymenopterism ultima.

At least 8 fractions have been isolated from bee venom. It contains histamine, but this is not considered to be the major pharmacological component. Two fractions, F1and F2 are basic protein components, with probable molecular weights of 35,000 and 44,000, respectively. Melittin (F1) accounts for most of the local and general toxicity, although the total effect is from the combined action of all components of the venom (Marshall, 1957). Melittin contains 13 amino acids, none of which contain sulfur. F2 is a slower-migrating fraction than F1 but supplements the effects of the latter, mainly through the 2 enzyme components. Habermann (1972) listed histamine and dopamine as the biogenic amines contained in bee venom, and the same compounds plus serotonin in wasp venom. He listed melittin, apamin, MCD-peptide, and minimine as the protein and polypeptide toxins (nonenzymatic) in bee venom, and "wasp kinin" in wasp venom. Among the enzymes, he listed phospholipase A, phospholipase B, and hyaluronidase as occurring in both bee and wasp venoms.

Based on published reports, Barr (1971) concluded that the causes of death from hymenoptera-sting allergy, in descending order of frequency, had been obstruction of the respiratory tract, acute vascular collapse, and vascular or hemorrhagic reactions, and that death had also been caused by various types of delayed reactions, frequently involving the central nervous system. Also, that in many older persons, an associated heart ailment had been a complicating factor.

Hymenoptera venom generally contains histamine, serotonin, acetylcholine, kinins, a hemolysin, a neurotoxin, a convulsant factor, hyaluronidase, other enzymes, and amino acids. Formic acid presumably accounts for most of the pain (Mueller, 1965). The LD50 of bee venom for 2 mains of mice was 1.75 mg/kg (intravenous) and 3.50 mg/kg (subcutaneous). Intravenous injection of dried bee venom in a saline solution produced a fall of blood pressure in dogs and monkeys in 35 seconds. Animals that survived returned to control levels within 5 to 30 minutes. Death resulted primarily from respiratory failure associated with some cardiotoxic action (Brooks and Vick, 1972). The most toxic component of bee venom is phospholipase A, which caused the death of a dog by respiratory paralysis in 10 minutes. It is similar to the phospholipase A obtained from Indian cobra venom, known to be a neurotoxin. Bee venom also contains melittin and apamin, which increase plasma cortisol. This could explain, in part, the observation that bee venom or some of its components alleviate the symptoms of arthritic-like conditions. This is a finding of special significance in that it suggests the possibility that fractions of bee venom might be used to control some of the symptoms of arthritis and thereby circumvent the high toxicity of whole bee venom (Vick and Brooks, 1972).

The immediate pain from a bee sting is of short duration; the swelling and itching that follow are the most disturbing. In some persons this does not occur, but susceptible or sensitized persons are so severely affected that they may be confined to bed for days. The combined stings of many bees, or the sting of a single bee in a sensitized person, may result in red blotches on the skin, shortness of breath, nausea, fainting, and even death. Even though bee and wasp vent)ms ordinarily have a relatively low order of lethality, they are great hazards to sensitized persons. This is a good example of severe autopharmacological action. The variability in the reactions of different people to insect stings is enormous. A beekeeper, whose wife and son suffered anaphylaxis whenever stung by bees, stated that he was stung without symptoms 200 to 300 times every summer. He rarely suffered generalized symptoms, and these only when stung on the scalp or neck. He would then develop generalized redness, pruTitis, and dizziness. He would be well after lying down in the field for a half hour. He suffered no reaction when stung on the extremities, and was convinced that the development or absence of symptoms depended on the site of the sting (Brown and Bernton, 1971).

The potency of honey bee stings varies with the time of year and with variation in the plants the bees are visiting. In California, the sting is most potent when bees are visiting California buckeye, Aesculus californica, the pollen and nectar of which are deleterious to both adults and brood (Eckert, 1940).

The Stinger Pheromone

When the bee stinger is protruded, it gives off a sweet scent reminiscent of the odor of banana oil. When the stinger is detached, as is ordinarily the case after a vertebrate animal is attacked, this odor is much greater. It is absent from the stingers of very young workers or queens. Because of the alarm and attack behavior which it releases in bees, the odor is considered to be a pheromone (Karlson and Butenandt, 1959). One of the constituents was found to be isoamyl acetate (banana oil), present in the amount of approximately I mug per stinger. When mixed with paraffin and absorbed in cotton balls, the isoamyl acetate alerted and agitated guard bees. Cotton balls that contained odoriferous stingers not only agitated guard bees, but incited them to attack, an additional reason for removing the stinging apparatus from the skin as rapidly as possible (Boch et al., 1962).

First Aid for Stings by Hymenoptera

When stung by a bee, remove the stinger, carefully scraping it off with a fingernail or knife blade to avoid squeezing more venom into the wound. When stung by any Hymenoptera, wash the site of the sting with soap and water and apply an ice pack to lessen local swelling. If infection, gangrene, or neuritis occur as complicating factors, additional appropriate local care is required. Hypersensitive persons should carry an emergency kit that can be used in the event of a sting and subsequent reaction while seeking professional medical aid. (See under "Treatment of Arthropod Bites and Stings" at the beginning of this chapter.)

Figure Captions

Fig. 226. Western yellowjackets. A, Vespula pensylvanica; B, Vespula vulgaris; C, Vespula atropilosa; D, Vespula maculata; E, Vespula arenaria; F, Vespula sulphurea. (All species have yellow markings on a black background except Vespula maculata, which has white markings.)

Fig. 227. Eastern yellowjackets. A, Vespula maculifrons; B, Vespula squamosa; C, Vespula vidua; D, Vespula germanica. (All species have yellow markings on a black background.)

Fig. 228. Faces of 2 yellowjackets. Top, Vespula maculata; bottom, Vespula pensylvanica. (The arrows indicate ocular-malar areas, which are long in the subgenus Dolichovespula (top) and short in the subgenus Vespula.)

Fig. 229. The most common western yellowjacket, Vespula pensylvanica.

Fig. 230. Ground nest of Vespula pensylvanica.

Fig. 231. Nest of Vespula pensylvanica with outer paper envelope removed to show combs and suspensoria. Inset: Some suspensoria (enlarged).

Fig. 232. Entrance hole of Vespula pensylvanica nest, with typical cleared area surrounding the hole.

Fig. 233. Nests of Vespula pensylvanica in houses. In an attic and in a wall void between 2 studs.

Fig. 234. Entrance to nest of Vespula vulgaris (left) and exposed nest in situ.

Fig. 235. Aerial nests of yellowjackets. Left, nest of Vespula arenaria attached to eaves; right, nest of Vespula maculata.

Fig. 236. Polistes fuscatus aurifer.

Fig. 237. Nests of Polistes fuscatus aurifer.

Fig. 238. Polistes fuscatus centralis.

Fig. 239. Apache wasp, Polistes apachus (worker).

Fig. 240.. Polistes dorsalis californicus.

Fig. 241. Above, Polistes exclamans arizonensis on a portion of its nest; below, the entire nest in its characteristic vertical position inside an orange tree.

Fig. 242. Polistes exclamans exclamans worker and nest - typical of the nests of most Polistes species. (From Wagner and Reierson, 1971.)

Fig. 243. Mischocyttarus flavitarsis flavitarsis.

Fig. 244. A solitary wasp, Pseudomasaris wheeleri. Top, an adult emerging from one of the cells in a nest of mud and sand attached to a twig; bottom, a female covering the last cell in a nest in which all cells have been provisioned with pollen and nectar. (Courtesy L. R. Brown.)

Fig. 245. Potter wasp, Eumenes iturbide pedalis, emerging from a pot on the stem of an Epidendrum orchid.

Fig. 246. One of the tarantula hawks, Pepsis mildei.

Fig. 247. Black-and-yellow mud dauber, Sceliphron caementarium, and mud nest attached at the intersection of a plaster ceiling and a rafter.

Fig. 248. A beautiful metallic-blue wasp (Chalybion californicum) that occupies the nests built by Sceliphron caementarium.

Fig. 249. A digger wasp, Ammophila murrayi.

Fig. 250. Cicada killer, Sphecius speciosus.

Fig. 251. Mutillid or velvetant, Dasymutilla satanas (female).

Fig. 252.. Scoliid wasp, Campsomeris tolteca (female).

Fig. 253. Food for the young of bees. A, egg of Apis mellifera in unprovisioned cell; young larva; mature larva. (The larvae are fed by workers.) B and C, eggs of solitary bees, Melitturga clavicornis and Systropha planidens, respectively, attached to pollen balls that will serve as food for larvae. (From Stephen et al., 1969.)

Fig. 254. Honey bee crawling away from her stinger left in the arm of a victim. (Courtesy Treat Davidson, from National Audubon Society.)

Fig. 255.. Swarm of honey bees attached to the limb of a shrub.

Fig. 256.. Honey bee colony in an attic.

Fig. 257. A window-screen cone placed over the entrance hole of a honey bee colony in a wall void. The escaping bee cannot return to the wall void, and will form a colony in the adjacent hive, which contains a queen. (From Stanger, 1967.)

Fig. 258.. Nest of bumble bees, Bombus morrisoni. A, old cocoons used for nectar storage; B, new queen cocoons; C, egg baskets on queen cocoons; D, cluster of young, developing brood; E, older developing brood; F, an original honey pot; G, young male bee; H, worker or male cocoon; I, egg basket on worker or male cocoon; J, worker bee; K, egg basket opened to show eggs; L, honey pot; M, probably a pollen pot; N, pollen pot; chicken feathers (the nest was in a chickencoop). (Courtesy W. P. Nye.)

Fig. 259. Sonora bumble bee, Bombus sonorus (worker).

Fig. 260. A worker of Morrison's bumble bee, Bombus morrisoni, collecting nectar from bladder senna, Colutea arborescens. (Courtesy W. P. Nye.)

Fig. 261. Leafcutter bee, Megachile davidsoni, and its wort A, adult; B, holes left where the bee cut disks from an avocado leaf;C, two columns of nests.

Fig. 262. Nest structures of 3 solitary nonburrowing bees (Megachilidae). A, Dianthidium concinnum; B, Megchile rotundata; lower left, Osmia species. [The first is from Stephen et al. (1969), after Fischer (1951); the second and third are from Stephen et al. (1969.]

Fig. 263. Nest-construction patterns of some burrowing bees. A, Systropha planidens (Halicitae); B, Andrena viburnella (Andrenidae); C, Andrena erythronii; D, Pedrita maculigera (Andrenidae); E, Paragapostemon mutabilis (Halictidae); F, Colletes micheneriacum (Colletidae); G, Perdita linualis; H, Halictus (Lasioglossum) dimorphos (Halictidae). (From Stephen et al., 1969).

Fig. 264.. The stinger of a worker honey bee. A, entire stinging apparatus, left side; B, end of a lancet; C, cross section of shaft of stinger; D, stinger in position of repose, suspended from wall of stinger chamber between spiracular plates (VIII T); E, stinger in position of protraction (arrows indicate the 2 essential movements); F, reproductive organs of a worker, together with shaft of stinger, stinger glands, and venom sac; a, attachment of quadrate plate with spiracular plate; b, apex of triangular plate continuous with lancet; BGld, "alkaline" gland of stinger; blb, bulb of stylet; c, hinge of triangular plate on quadrate plate; d, hinge of triangular plate on oblong plate; h, hinge of bulb; Lct, lancet; Ob, oblong plate; Odl, lateral (paired) oviduct; Ov, ovary; pc, venom canal; PsnGld, venom gland of stinger; PsnSc, venom sac; Qd, quadrate plate; Ir, basal arm (ramus) of lancet; 2r, basal arm of bulb and stylet; Sh, sheath lobes; Shf, shaft of stinger; Sp, spiracle; Spt, spematheca; Stl, stylet; Stn, stinger; Tri, triangular plate; VIII T, spiracular plate associated with stinger base. (From Grout, 1949.)

1996; 2002© Entomology UC Riverside
Last updated on Aug 23, 2002 by leowest@ucrac1.ucr.edu