Although keratin-containing substances (wool, hair, and feathers) are their preferred food materials, carpet beetles and clothes moths will also attack other fabrics, such as cotton, linen, silk, and synthetics if the fabrics contain contaminants of nutritional value, such as urine, perspiration, beer, milk, or fruit juice. Merely handling a fabric with the bare hands will impart some nutritional factors to it, and even fungus spores settling from the air will add some nutrition (Pence, 1958). Clean, processed wool cannot support the normal life cycle of the clothes moth unless it is contaminated with certain nutritional supplements.
In one investigation, it appeared that minerals, proteins, and B vitamins were the attractant substances in fabric stains for the larvae of the webbing clothes moth, Tineola bisselliella, and the furniture carpet beetle, Anthrenus flavipes. Of the salts tested, K2HPO4, KCl, NaCl, and Na2HPO4 were the most readily eaten, and appeared to be the substances that would make a stain such as tomato juice attractive to these insects. However, the larva of the black carpet beetle, Attagenus megatoma, was not especially attracted to these salts or to the more common stains (Mallis et al., 1962).
There are many species of insects that are unable to digest keratin, but nevertheless can cause damage by chewing through keratin-containing fabric. Termites, crickets, cockroaches, silverfish, psocids, and even some dermestids may be included among such species.
Wherever they occur, the fabric-infesting insects are potentially highly destructive, but the substitution of synthetics for many of the woolen fabrics and the treatment of rugs, carpets, and other woolen fabrics with insectproofing agents in their places of manufacture have led to a steady decline of the over-all importance of this group of household pests. However, the hazard remains undiminished for unprotected furniture and fabrics imported from areas of the world where they are not treated. Even initially protected materials can lose their immunity to attack through cleaning and aging.
The source of a carpet beetle infestation is sometimes difficult to find. For example, one pest control operator treated an office building 3 times, each time failing to find the source of the beetles seen by the occupants. On the fourth attempt, he traced the beetles to a telephone cable in the wall, where the insects were discovered to be feeding on the insulation.
Whereas clothes moth larvae usually are found on their food material, carpet beetle larvae crawl about for considerable distances, and may be found on cotton goods or other materials on which they do not feed. They may often be found behind baseboards and moldings, in cracks in floors, behind radiators, in the air ducts of heater systems, and other secluded areas. If found in one area of a house, such as in the carpeting of a hallway, they can be expected to be found in adjoining rooms also. The adults and larvae of carpet beetles may also be seen outdoors in and under dead animals, in the hides and horns of cattle, or in the nests of birds, rodents, wasps, or bees (including the honeycomb). Beetles or clothes moths originating in such materials under floors or in wall voids or attics sometimes invade the living space, and the originally infested materials may continue to be sources of infestation after carpets and other infested articles have been treated (Linsley, 1944). The cast skins and fecal pellets of such insects in the attic sometimes drop into the rooms below via apertures around beams, through the holes in perforated ceiling tile, and around light fixtures. This material is sometimes mistaken for the frass of woodborers, and may lead to a mistaken diagnosis of the problem.
Although the larvae can eat large holes through any suitable food material, they tend to eat the nap from the fabric and shun the base threads. In furs, they tend to cut hairs at the base with no injury to the hide, but they leave it bare in appearance. The larvae may also burrow through packaging material to obtain food, thus providing access for other species of insects (Truman and Butts, 1967).
Description. The adults (plate VI, 2; figure 201, A) are 2.8 to 5 mm long, shiny black and dark brown, with brownish legs. The full-grown larva is narrow, up to 8 mm in length, tapers toward the rear (carrotshaped), terminates in a tuft of long hairs, and has short, stiff hairs covering the body. It varies from light brown to almost black. The cuticle is hard, smooth, and shiny, resembling that of a wireworm. It is relatively resistant to pesticides.
Life Cycle. The number of days required by the various stages are: egg, 6 to 16; larva, 166 to 330; and pupa, 8 to 14. The period from egg to adult is 180 to 360 days, and the adult may live another 30 to 60 days (Laudani, 1961).
The female lays about 90 eggs in the lint under and behind baseboards, in cracks, in ducts of hotair furnaces, and other dark and protected places. There may be 5 to 11 larval instars, or even as many as 20 under particularly favorable conditions.
Description of Anthrenus verbasci. This species has a number of varieties. They differ in shape, size, color, and pattern of the scales, but in general the adults are 2 to 3 mm long, and have a varied pattern of white, brownish, and yellowish scales on the back and fine, long, grayish-yellow scales below (plate VI, 3; figure 201 B). Where ihe elytra terminate, they do not form a cleft as do those of the furniture carpet beetle, A. flavipes. The mature larva (plate VI, 2) is 4 to 5 mm long, and has a series of light- and dark-brown transverse stripes. If it is suddenly alarmed, the larva erects the 3 dense tufts of bristles and hair located on each side of the rear end of the body, spreading them out to form beautiful, round plumes (Back, 1938). The larva is broadest near the rear, and becomes narrower toward the front end, unlike other carpet beetles.
Life Cycle. The female lays about 40 eggs. There are usually 7 to 8 larval instars, but the number may vary from 5 to 16. The numbers of days for the various stages are as follows: egg, 17 to 18; larva, 222 to 323; and pupa, 10 to 30. The period from egg to adult is 249 to 354 days, and the adult may live another 14 to 44 days (Laudani, 1961).
Description. The adults (plate VI, 1; figure 201, C) are 2 to 3.5 mm long, spotted yellow, white, and black above and white beneath. They are slightly larger and more rounded than the varied carpet beetle, and have a cleft where the elytra meet posteriorly. The adult spends a quiescent period within the old larval skin before becoming active. Recently hatched larvae are white, but turn light yellow to dark red or chestnut brown as they develop. They are about 5 mm long when full grown. They are widest in front and become narrower toward the rear. Mature larvae are darker than those of the varied carpet beetle, and are able to run swiftly.
Life Cycle. The female lays about 60 eggs in from 1 to 3 clutches, generally in such places as the pile of mohair chairs, in the nap or on the surface of clothes, and in cracks and crevices. The numbers of days for the various stages are as follows: egg, 9 to 16; larva, 70 to 94; and pupa, 14 to 17. The period from egg to adult is 93 to 126 days, and the adult may live another 30 to 60 days (Laudani, 1961).
Description. The adult is 3 mm long, gray to black, with a varied pattern of whitish and orange scales on the back, and with whitish and orange-red scales around the eyes and on the clypeus. The mature larvae are about 3 mm long, reddish brown, and have many black or, brown hairs. They move about actively.
Life Cycle. The female lays about 60 eggs on textiles or other larval food sources. The number of days for various stages are: egg, 10 to 18; larva, 60 to 80; pupa, 7 to 12. The period from egg to adult is 77 to 110 days, and the adult may live another 20 to 30 days (Laudani, 1961).
The larvae somewhat resemble those of the common carpet beetle, but lack the tuft of hair at the rear end and the long hairs on the dorsal surface. Instead, there is a transverse row of stout bristles at the rear edge of each body segment, those on the prothorax being clubshaped. The larva can roll itself up into a ball when disturbed. The larvae feed on dry animal matter and woolen, silk, or muslin cloth, even when it is unsoiled. They can penetrate tissue paper used to wrap their normal food materials, but the common name "tissuepaper beetle" does not appear to be appropriate.
Besides feeling on clothes, carpets, rugs, and upholstered furniture, the webbing clothes moth feeds on furs, stored wool, and such miscellaneous articles as the animal bristles of brushes and the felts in pianos. In nature, it feeds on pollen, hair, feathers, wool, fur, dead insects, and dried animal remains.
Description. The body and wings of the adult are uniformly golden colored, except for reddish golden hairs on the top of the head (plate VI, 4; figure 202). The wingspread of the female is about 11 mm and that of the male is somewhat less.
Life Cycle and Habits. The adults are very active, can penetrate through surprisingly narrow cracks, and can fly considerable distances (Griswold, 1944). However, they are not attracted to light, and gravid females are weak fliers. The female dies after attaching about 40 to 50 eggs, singly or in groups of 2 or more, to the threads of infested clothes over a period of 2 to 3 weeks. The eggs (figure 202, inset) hatch within an average of 4 to 10 days in summer, but take as long as 3 weeks in winter.
The newly hatched larvae are only about 1 mm long, and translucent white. Some larvae may spin a small, frail, silken tube or tunnel, incorporating into the silk some fibers, excrement, or cast skins. They then feed within the confines of the tube. Others may merely spin flat mats under which they crawl about, or remain naked for several days before they spin any webbing. Some larvae leave the webbing and crawl about unprotected. The feeding tubes and silken mats make up the webbing that characterizes an infestation. The number of larval molts can vary from 5 to 45, and the period required for larval development can vary from 35 days to 2.5 years, depending on the availability of food as well as relative humidity and temperature. The full-grown larva is shiny, creamy white, and about 12 mm long. When preparing to pupate, it spins a pupal case of silk about 8 mm long, again incorporating textile fibers and excrement. The period required for pupation varies with temperature, but can be as brief of 8 or 10 days in summer or as long as 3 or 4 weeks in winter. The length of the life cycle varies from 50 to 90 days, but can be extended to as long as 4 years under unfavorable conditions (Back, 1923).
Description. The adult is somewhat smaller and more brownish than the webbing clothes moth, and has 3 dark spots on the wings, but the spots become less discernible if the wing scales are worn off. The hindwings are yellowish brown. The males are smaller and lighter in color than the females, and are active fliers. The females are sluggish, and fly only for short distances. The first thoracic segment of the larva, at first brown, later becomes black, and is divided by a longitudinal band.
Biology. The larva can turn within its case and feed on food material at either end without altering tlie position of the case. If the case is removed from the larva when it is very near pupation, the larva will die. Rarely will the larva spin a web directly on the material on which it is feeding, but will usually attach its case to the material by means of silken threads. Pupation takes place within the case after both ends have been sealed with silk. There were found to.be 3 or 4 generations a year at 26 ° + 8 °C (79 °F) and 82% +10% relative humidity when larvae were fed on woolen fabrics impregnated with 5% yeast (Cheema, 1956).
Abandoned nests of birds, rodents, and insects. (particularly bees and wasps) that are in or near the house should be removed, for the larvae of both carpet beetles and moths may feed on insect remains that they may contain. Bedding places of pets should be kept clean. Mounted animal specimens or trophies (or even fur-covered toys), insect collections, stored woolens, carpeting, clothing, feathers, furs, old spices, cereals, or seeds should be examined for signs of infestation. The attic and garage should be included in the inspection. Avoid bringing carpet beetle adults into the house on cut flowers, where they are sometimes found feeding on pollen.
Dry-cleaning kills all stages of clothes moths and carpet beetles, but gives no protection against reinfestation. Many cleaning establishments and pest control firms can apply protective treatments. Woolen garments or materials that have been stored for a long time should be occasionally shaken and aired. Brushing can crush most eggs, particularly the fragile eggs of carpet beetles. If they cannot find protection from light, many larvae that are not removed by the brushing will fall from any garments hung in the sun, as on a clothesline. (It is unwise to use such treatment for furs, since they are subject to fading, drying, or even theft.)
Woolen clothing and blankets can be protected against feeding damage by carpet beetles and clothes moths by spraying them lightly with oil solutions of methoxychlor or allethrin (Bry et al., 1968); Gardona
Woolens stored in a container, trunk, or closet may be fumigated with paradichlorobenzene (PDB) crystals and naphthalene flakes or balls (mothballs). The storage container should be tightly sealed. Loose-fitting containers can be lined with heavy paper and sealed with tape. One lb (0.45 kg) of either fumigant is enough to treat 20 cu ft (0.57 cu m) of storage space. Scatter the fumigant between the layers of paper separating the articles to be treated. In a reasonably tight container, 1 application a year should suffice. In closets, apply the fumigant to the floor and shelving, and replenish the supply after it evaporates. All plastic buttons should be removed from clothing before treating, and plastic hanger's should not be used, for PDB and mothballs are destructive to plastics and may fuse them with the fabrics.
The 20% Vapona Resin Strip (polyvinyl chloride resin impregnated with dichlorvos) is worthy of trial in almost any situation in which the pests are in a confined area. The strip slowly gives off vapors of dichlorvos, which is much more toxic to insects than PDB or naphthalene, less toxic to man when used as directed in limited storage areas, and is also less expensive. Either the 6-in. (15-cm) strip or the 2-in. (5-cm) "ministrip" can be subdivided to the appropriate size for the space to be fumigated. In a small, tightly scaled container, such as the Schmidt box in which pinned insects are kept, vapors leave a piece of Vapona Resin Strip very slowly because of vapor pressure built up in the box. As little as 1 sq in. (6.45 cm
Woolens wrapped in heavy paper or enclosed in a cardboard box with sealed edges are protected against fabric pests, provided the woolens are not already infested. Spraying of furs is not recommended, for they can be protected with PDB, mothballs, or dichlorvos resin strips as recommended for woolens, or they can be frequently shaken and aired. If living or dead insects, fecal pellets, cast skins, or fiber particles are not present, as they would not be after the fur is brushed, shaken, or cleaned, mandibular scars on the individual fibers are unmistakable clues to insect damage. An illustrated guide for the diagnosis of fur damage with the aid of a microscope is available (Pence, 1966).
The edges of rugs or carpets can be pulled up and the common household sprays can usually be applied on both sides, as well as on both sides of the pad. Treatment is particularly important under heavy furniture that is seldom moved. Upholstery and draperies can be sprayed, following the same directions discussed for clothing and blankets.
Pesticide sprays may be applied to any surfaces upon which fabric-infesting insects are likely to crawl, such as along the edges of wall-to-wall carpeting, in closets, behind radiators, and in corners, cracks, baseboards, moldings, and other hard-to-clean places. Closets, particularly, should be thoroughly sprayed after removing the contents. Chlordane 2%, premium grade malathion or ronnel 5%, and lindane or diazinon 0.5% have been recommended as insecticides (USDA, 1966). Insecticide dusts are useful to blow into attics, basements, wall voids, or other areas difficult to reach with a spray, or dusts may be sprinkled on the floor and swept into cracks, after which the rug can be put back into place.
Deodorized kerosene (base oil) with dissolved insecticides, when applied as a mist or fog, remains as an oily deposit on the surface of a carpet. The addition of 30 to 50% of isopropyl alcohol (rubbing alcohol) results in good penetration of the insecticide to the bases of the fibers, where fabric pests feed (Pence and Viray, 1963). Oils can cause the nap to separate from the backing, and then the carpet buckles. By improving penetration, the isopropyl alcohol reduces the amount of oil required and decreases the possibility of damage to the carpet. Only enough spray should be used to reach the bases of the fibers, and any excess should be avoided. A kerosene-isopropyl alcohol solution should be used only for treatment of carpets and rugs - not as a space spray. Windows and doors should be left open during application. Pilot lights should be extinguished before treating near floor or wall furnaces, hotwater heaters, or other natural gas appliances.
Water-base sprays can be effectively used if a wetting agent is added. Such sprays should not contact nonwashable wallpaper or other materials that will color-run or stain.
Fumigation is an effective method for the control of fabric pests. If the pests are widespread in a house, the entire building can be fumigated by a pest control operator. Fumigation is expensive, and requires that the house be vacated for a day or two. It provides no residual protection against reinfestation. Some pest control operators and storage firms have fumigation vaults where infested pillows, mattresses, upholstered furniture, and similar small articles can be fumigated when the infestation is localized. Methyl bromide, the most commonly used gas for fumigating buildings, is known to be a good ovicide. It was found to be effective against all stages of carpet beetles (Pence and Morganroth, 1962).
According to a more recent report from the same laboratory, when resmethrin was applied to woolen cloth as an aerosol, it protected the cloth against feeding by black carpet beetles and webbing clothes moths for as long as 6 months (Bry et al., 1973a). These 2 species were also killed when hit by the resmethrin aerosol. This versatile and relatively safe synthetic pyrethroid shows promise as a replacement for some insecticides now used in the home against carpet beetles and clothes moths (Bry et al., 1973b).
Silverfish are nocturnal insects that may occur almost anywhere in a house, including attics, wall voids, and subfloor areas. They are very fastmoving, and sometimes are seen only when they are trapped in such places as washbasins and bathtubs, where they remain because they cannot climb smooth, vertical surfaces.
Silverfish feed on any human food, and in addition they may feed on starch, paste, glue (as in bookbindings), starched cotton, linen, silk. or certain synthetic fibers and paper products (figure 205), to which they are attracted by sizing or, as in the case of wallpaper, by paste. Sometimes they cause wallpaper to flake off by removing the paste. Possibly, the most common evidence of the presence of silverfish is paper with the glaze removed in an irregular fashion, with irregular holes, or with the edges notched. Scales, excrement, or yellowish stains may be seen on paper or fabric that has been infested. Silverfish may also feed on dead animals, including dead or injured individuals or cast skins of their own species.
As might be expected, silverfish are serious pests in libraries, where they attack bookbindings and heavily sized paper. They seldom injure wool, hair, or other fibers that are of animal origin. Like termites, they are said to harbor organisms that aid them in the digestion of cellulose materials. A silverfish infestation develops slowly, so when these cryptobiotic insects become numerous enough to be seen occasionally in a home, this indicates that the infestation is probably an old one, or that large numbers were brought into the home as eggs, active stages, or both, in cardboard cartons, books and papers, and other household materials. All the species described in this chapter are in the family Lepismatidae.
Description. This is a silvery-gray insect with a metallic sheen (plate V, 5; figure 206). It attains a length of about 12 mm, not including the appendages.
Life Cycle. According to Sweetman (1939), females might lay 1 to 3 eggs per day on a number of successive days or at intervals of several days or even weeks. Wigglesworth (1964) stated that the female alternately molted and laid eggs, and might molt up to 50 times before becoming an adult. He found that the eggs hatched in 50% relative humidity at 22 and 27 °C (71 and 80 °F), but only above 75% RH at 29 and 32 °C (84 and 90 °F). He noted that the period from egg to adult could be as long as 2 or 3 years or, under favorable conditions, only 3 or 4 months. Development was favored by warmth and high humidity. Sweetman also observed that at temperatures ranging from 22 to 32 °C (71 to 90 °F), nearly all reproduction occurred at above 75% RH, and the highest percentage of oviposition took place at 84 to 100% RH. This insect may continue to grow for well over 3 years, molting every 2 or 3 weeks.
Description. This insect is only slightly larger than the silverfish, being about 14 mm long, silvery, but with transverse gray areas that give it a mottled appearance (plate V, 6). When its scales are rubbed off, the light-yellow color of the body can be seen.
Life Cycle. At temperatures of 90 to 106 °F (32 to 41 °C), the female may oviposit when she is 45 to 135 days old, depositing her eggs in crevices, an average of about 50 in a lifetime. Like the silverfish, the firebrat continues to molt during its adult life. Only 1 clutch of eggs is laid between molts, and fertilization must take place before each clutch of eggs is laid. The elliptical, nearly white eggs are about 1 mm long and 0.7 mm wide in their greatest dimensions. Optimum conditions for incubation of eggs are 99 °F (37 °C) and 76 to 85% relative humidity, and eggs kept at these conditions will hatch in 14 to 18 days. Under optimum conditions, only 1 day or less is spent in the first instar, 4 in the second, about 6 in the third and fourth, and about 8 in the fifth to tenth. This period gradually increases to 12 or 13 days in further instars, and the insect may pass through 45 to 60 instars before death (Sweetman, 1938). Brett (1962) found that females started to oviposit in the fourteenth instar, and that molting of the growing firebrats appeared to be continuous, with very little change in size occurring after the thirty-fifth instar.
A curious and noteworthy thing about firebrats is their "love dance," described by Brett as follows:
The courtship of firebrats has been described as a "love dance" wherein the male constantly approaches the female. and repeatedly contacts her antennae, mouthparts, and legs. As the male whirls about, he curves his abdomen and deposits a sperm bundle about one-half inch in front of the female. He then contacts her head and legs and comes to rest, apparently losing all interest in her. After his final contact, the female moves forward, straddles the sperm bundle, and secures it to certain reproductive structures.At 37 °C (99 °F) and 50 to 70% relative humidity, firebrats have been reared both with and without liquid water to imbibe, but in one experiment the insects reared with water weighed 50% more than those receiving none. Firebrats can obtain water from wet cotton wicks, but they avoid actual drops of water on the wick. Without access to water, development is slower, and oviposition is retarded and decreased (Adams, 1933). At ordinary room temperatures, firebrats lose water from their bodies only below 45% RH; above that, they absorb water via their cuticles (Noble Nesbitt, 1969).
Lepisma saccharina and Thermobia domestica are seldom seen outdoors in temperate regions, but have been occasionally found under bark, in bird, mammal, and insect nests, and in debris (Linsley, 1944).
Description. The fourlined silverfish is about 15 mm long, tannish gray, and has 4 dark lines extending down the length of its back. The young are light brown, and are often tinged with pink until the fourth molt, which occurs a month or so after hatching. The subspecies Ctenolepisma lineata pilifera (Lucas) frequently enters homes in rural areas of northern California (Smith, 1970).
Dietary Factors. This species is the most widely distributed and abundant silverfish in Australia, where its biology was intensively investigated by Lindsay (1940). In wallpaper, the palatable materials were the starch and dextrin sizes on the surface. In writing paper, the palatable material was the "chemical pulp" containing degraded celluloses. Papers containing more than 45%, "mechanical pulp" were not eaten; the unpalatable materials were associated with the "ether extract" fraction. Cellulose-digesting bacteria, and enzymes that passed forward from the midintestine, supplemented the action of the gizzard in the digestive process.
In recent years, pest control operators have had increasingly erratic results with chlordane against the firebrat. In laboratory tests, residues of chlordane gave less than 100% mortality on a porous surface (unfinished plywood) in 144 hours when used at less than 4% concentration, whereas diazinon, dichlorvos, malathion, and propoxur gave 100% kills in 24 hours used at 0.25, 0.25, 1.25, and 0.55% concentration, respectively. By far the most effective insecticide tested in both topical and residual treatments was chlorpyrifos (Dursban
In the author's experience, when treating mixed populations of cockroaches and silverfish, a thorough cockroach control has invariably eliminated silverfish also. However, Lepisma saccharina and particularly Thermobia domestica may occur in very localized infestations, and treatment can be confined to the areas where they are known to occur. For firebrats, emphasis is placed on treatment of areas of high temperatures, such as around heating units, heating pipes or conduits, steam or water pipes, and fireplaces (Zeigler, 1955). Ctenolepisma lineata is more difficult to control because it is so widespread both inside and outside the house.
The fourlined silverfish particularly, and sometimes other species, may be found in attics. Dri-die is so light that it can be uniformly blown throughout the attic from a single crawl hole. Because it is inorganic, it affords protection against silverfish and other attic-infesting pests for much longer periods than the conventional organic pesticides.
Most of the various insecticide dusts can be used effectively to eliminate existing infestations. For attic dusting, electric blowers (figure 32, chapter 3) or water-type fire extinguishers (figure 33, chapter 3) can be used, and the latter, because of the narrow discharge orifice, can also be used for blowing dust into wall voids or under cabinets through existing apertures or through holes that may be drilled in appropriate places.
Among fabrics, silverfish do most damage to rayon. Zeigler (1955) noted in several cases of damage to rayon draperies that most of the holes made by the fourlined silverfish were made at windowsill level. He noticed that the insects were often found between the drapery and its lining. A light mist of residual pesticidal spray can be applied to cornices and both sides of the infested draperies.
Poison Baits. Adams (1933) found that the odor of ground rolled oats, which was generally considered to be a favored food of firebrats, did not attract them at a distance of 8 cm, even after the insects had been denied food for 2 days. Direct antennal contacts were required for strong, positive responses to dry food particles. This probably accounts for the very poor results the author has had in attracting firebrats to currently popular poison baits when the baits were placed in traps on the centers of the floors of enclosed wooden boxes 29 cm long, 14 cm wide, and 9 cm deep, even when other food sources were absent. A few insects would invariably live longer than 25 days without being attracted to the bait. Many firebrats congregated on the vertical walls of the boxes, and were seldom seen crawling over the floors. Contacts with baits were probably by chance. This was in accord with the observation of Berger (1945) that the location of a baited trap, and not the bait, determined the number of firebrats caught. The same is probably also true of other silverfish species. When placing poison baits in areas where silverfish normally crawled, Berger found that among equally available foods, the firebrats showed preferences. He concluded that because of the ease of mixing and their availability, wheat flour 85% and powdered sugar 15% were about the most practical food combination for bait. However, another factor to be considered is the repellency of the insecticide in the bait. For example, Mallis (1941b) found that Ctenolepisma longicaudata was repelled by white arsenic, sodium arsenate, sodium fluosilicate, and sodium fluoride in flour pastes, but not by barium fluosilicate or barium carbonate.
Traps. Where the application of insecticides is undesirable, silverfish can be trapped. The outer surface of a small jar, such as a 1-oz ointment jar, can be covered with masking tape to enable silverfish to climb up the outside of it. The insects fall into the jar, and cannot escape because they are unable to climb its smooth, vertical walls. The traps should be placed in paths normally used by silverfish, as in the intersections and corners of a pantry or bookcase or next to the baseboard on the floor (in the warmest locations, in the case of firebrats). The first to advocate a trapping procedure for firebrats was Mallis (1941b), who placed a teaspoonful of white wheat flour in the jar. In our replicated laboratory experiments with large numbers of firebrats, we found that the trap jars had to be judiciously placed, as in corners of the experimental boxes, but that the kind of bait used had no influence on the number trapped. Empty jars trapped as many firebrats as jars with wheat flour and sugar or wheat flour, sugar, and chipped beef.
Mallis et al. (1958) observed that the carpet beetles fed slightly on nylon, but the clothes moth and the firebrat did not. None of the 4 species they tested did any damage to dynel, dacron, orlon, vicara, or cotton percale. However, any fabric was attacked when contaminated with nutrient material, such as starch, beer, urine, fats, and molds. Stains containing minerals, proteins, and B vitamins caused fabrics to be more attractive, even those that would otherwise not be infested. The predilection of firebrats for viscose rayon noted by Mallis et al. had also been demonstrated by Wall (1953) for both the firebrat and another species of silverfish, Ctenolepisma lineata.
Most of the termites that normally feed on wood eat fabrics of cotton, linen, jute, silk, rayon, and leather. Termites coming up through the floorboards and joists can damage carpets (Harris, 1961). Termites may destroy materials they do not use as food but which are damaged when the insects bore through them or pack earth against them. The termite Cryptotermes brevis readily attacks cellulose fabrics (Light, 1934a, b). Termites, crickets, and silverfish will attack cotton, especially if it is starched or soiled (Labarthe, 1964). Sometimes, the injurious insect destroys the fabric to gain access to fibers in building a nest or cocoon, e.g., damage from the fan palm caterpillar, Litoprosopus coachellae, as already described (figure 204).
There are many cases of damage to fabrics merely because they are in the way of insects. An example would be carpeting damaged by termites and the adults of woodwasps and certain woodboring beetles, when it happens to be in the way of insects emerging from the wood floor. The insect must bore through the fabric in order to escape. A rare and curious type of damage was reported from a home in which insect damage to a man's suits had amounted to about $1,000. Drugstore beetles (Stegobium paniceum) (figure 193, chapter 7) infesting cayenne pepper in the kitchen pantry had apparently found their way to a clothes closet, via the wall voids, and emerged in the closet to gather on a shelf. They dropped from the shelf onto the right shoulder of each suit, cut their way through the fabric, and dropped to the floor. Removal of the infested spices and spraying of the closet prevented further damage (Cushing, 1970).