Fabric Pests
Winter is the time when you may take out your heavier clothes, which have usually been stored away for months. Sometimes, you will find there are holes or spots where the fur or wool liner of a coat looks “worn” or thinner than it used to be. If you look close enough, and there are little “worms” or tiny oval beetles crawling around near those holes or spots, then you have one of several fabric pests. There are several common, widespread insects that eat holes through fabrics or carpets. Most common are the clothes moths and carpet beetles. One common and widely distributed such beetle is discussed below.
Varied Carpet Beetles probably received their name because of the varied color pattern on their back. Adults are small, hard-bodied, oval beetles, about 1/16-1/8 inch long. Their body is black, covered with a pattern of yellow and white scales. When seen from above, there are two zigzag bands of white scales bordered by yellow scales across the back. The scales are 2-3 times as long as broad. The underside of the body is covered with grayish-yellow scales. Antennae are short, with a 3-segmented, compact club. Their head is more or less concealed from above and has a median simple eye. These are found worldwide. Adults are strong fliers and mainly feed on a wide variety of outdoor flowers, pollen, or plants. They may come into houses or businesses and deposit their eggs on nearly any natural animal or plant materials, on which the larvae then feed. Often they select fabrics such as wool, cotton, or as their name indicates, carpets which contain any natural organic fibers. The adults do not eat fibers and usually die in 13-44 days, before finding their way back outdoors. Larvae of these beetles are up to ¼ inch long, stout, brown-to-black, and covered with a lot of brown hairs. There are tufts of special spearheaded hairs (hastisetae) on top, near their back end. These hairs can cause the skin of humans or pets to itch badly.
Larval feeding is what causes all the damage. Fabrics infested by Varied Carpet Beetles typically have a lot of surface damage and a few holes here and there, but larvae can sometimes eat large irregular holes in material. Furs and brushes have mostly the tips of hairs damaged, leaving uneven areas. When they invade museum specimens, or other dead insects, the accumulation of fine powder (frass) under or beside the insect body is often the first indication of this beetle’s presence. Larval skins that have been shed are usually present, too. Larval frass is a fine, irregular powder, often the same color as the material being eaten. Larvae may burrow through packaging materials when seeking food. They may be found in bird or animal nests; in or near carcasses; in accumulated dead insects, hair, or ling; and even in the nests of social bees and wasps. These larvae may wander a long way from the site of the mainly infested material, when they are looking for a place to pupate, or when their population is large.
The Varied Carpet Beetle’s life cycle (egg-to-egg) usually takes about 265-380 days, depending very much on temperature, moisture and available larval food, but it may take 2-3 years. Females do not always lay their eggs directly on larval food material. When larvae hatch 17-18 days later, they may have to search around for a food source. Larvae usually go through 7 or 8 molts but that can vary from 5 to 15. Adults hatching from pupae indoors avoid light until they mate and finish laying their eggs. They then become attracted to light. Most adults found outdoors are attracted to light.
The key to controlling Varied Carpet Beetles, and similar fabric pests, is to find the primary site of the infestation and eliminate it. Besides the obvious clothing, furs, drapes, carpeting, and stored products, it may be necessary to check for more unusual places such as those mentioned above. You must try to remember any current or past occurrences of flies in the winter, box elder bugs, rodent problems, birds nesting on or in the building, etc. A thorough inspection should be followed by good sanitation practices, and pesticide application when required. Infested materials such as rugs or tapestries may be treated with heat or cold if applicable using the same temperature ranges as suggested in the story about stored products pests (be careful of possible damage to the material) or with fumigants.