In This Issue...What's “Bugging” You? Part 2
Habits – Lifestyle, Appearance & Evidence
Adult insects deposit their eggs in all sorts of locations—clothing, upholstery, rugs, toys, animal skins, trophies, and even natural bristle brushes. They prefer to feed in areas that are dark and undisturbed such as closets, attics and storage boxes. Things in constant use or frequently vacuumed, rarely get damaged, but watch those unused areas of a rug next to walls or under furniture! Even air ducts are a popular breeding area! As the eggs hatch, the larvae will look for any animal-based material to feed on: silk, wool, leather, dog and cat hair, feathers, and even wool blends or synthetics that may contain food stains, urine, hair oils, sweat or body oil residue.
The eggs and larvae, as well as adult insects, enter your home in a wide variety of ways – on your clothes, pets, shoes or they may fly in through an open door or window. Articles containing wool or other animal fibers, upholstered furniture, woolen fabrics and rugs are popular avenues. Be especially wary of used clothing or furniture, and items purchased at antique stores, vintage stores, yard sales or on-line auctions.
Adult clothes moths prefer darkness and hide very quickly if disturbed. They are definitely NOT the moths you see attracted to lights! Clothes moths are light tan, about 1/2” long and have very narrow wings. Adult carpet beetles, in contrast, love the sunlight and are known to feed outdoors in your garden on the pollen and nectar of flowers, especially Spirea, asters, dahlias, daisies, sunflowers, Virburnum, Caeothus, goldenrod and the flowers of wild and cultivated fruits. They’ll enter your house with these blossoms, or fly through an open window or door! The most common ones are small, oval-shaped and mostly black with varied patterns of orange and white. Carpet beetles are often mistaken for a common garden “lady bug,” but they are about 1/4 to 1/2 the size.
Silverfish, a primitive-looking 1/4” long, silver-colored wingless insect, is probably related to something that crawled up on land 300 million years ago. In North America they are almost exclusively associated with human habitation, and reside in houses and stables. They are quite prevalent in kitchens and bathrooms, for they require very high humidity or access to water. They thrive on the tiniest scraps of food. Although they prefer starchy food, they are quite able to digest cellulose and will devour your books and Christmas decorations as eagerly as the food stains on your garments!
Life Cycle, Appearance & Evidence
Webbing Clothes Moths (Tineola bisselliella)
Probably more common than the casemaking clothes moth, the Webbing Clothes Moths spin a silken web to form feeding tubes, which they attach to the items being eaten. The body of the adult moth is covered with shiny, golden scales and the top of its head has a tuft of fluffy, reddish-gold hairs. It has black eyes, its antennae are darker than the rest of its body, there are no spots on its wings, and females are slightly larger than the males. The female lives about 15 to 30 days and lays 40 to 50 large eggs (relatively speaking, 1/24” long). The eggs are translucent and quite vulnerable to physical damage. Her nest may be very hard to spot as she will lay a layer of camouflage web or casing over the eggs and developing larvae that blends into its surroundings, hiding it in the fabric. Look for webbing, cocoons, cases, copious amounts of tiny pellets, and even dead moths clumped into the webbing. In addition, the droppings may be the same color as the fabric being consumed, making the evidence even harder to spot. This “nest” may look like a harmless piece of lint.
Depending on the temperature and season, the eggs hatch into larvae in 4 to 30 days. These worm-like larvae are shiny, creamy-white and about 1/2” long when mature. The larvae spin silken feeding tubes as they feed, and reach maturity in 35 days to 2.5 years. This great variation in time is dependent on food, temperature and humidity. In a warmer climate, the clothes moth larvae live for at least two months. The perfect environment for clothes moth development is 75% relative humidity in a heated, dark room. The adults don’t eat, so larvae must consume enough so the adults may complete their life-cycle. The larvae change to a pupa and live inside silken cases they make as they mature into adults. This pupal stage may last from 55 days to as long as 4 years! Under normal conditions it’s usually from 65 to 90 days. The adult emerges from the pupa to start the life cycle again, generally about 2 generations per year.
Casemaking or Case-Bearing Clothes Moths
Casemaking or case-bearing clothes moths are slightly smaller than the webbing clothes moths. The adult is light brown with 3 barely visible dark spots on each wing. The adults live for only 4 to 6 days. The females lay 37 to 48 creamy-white oval-shaped eggs (photo on left), which soon turn red, and hatch in 4 to 7 days into larvae which look like cream-colored caterpillars less than 1/2” long. During the larval stage, which lasts 68 to 87 days, they spin protective cases (using bits and pieces of items they’re consuming!) and drag the cases along as they move (it’s an “insect RV”!). (Below: Larvae & cases) Eventually the cases become the tough cocoons in which the pupae develop into adult moths in 9 to 19 days. Evidence of their presence is similar to the webbing clothes moths. Other less common moths include the Brown House Moth, and the Tapestry Moth, both of which require at least 80% humidity to thrive.
Carpet Beetles (Anthrenus verbasci & Attagenus pelio)
Carpet beetle adults live 20 to 60 days. The female lays 30 to 100 eggs on a surface sure to provide good nutrition for the growing larvae. Those larvae hatch in 6 to 20 days and live 60 to 325 days. The pupal stage lasts 10-17 days. The average life is about 9 months! Carpet beetle larvae measure 1/8” to 1/4” long and appear to be densely covered with tiny hairs or bristles.
They molt several times during their life cycle, leaving behind skin casings, which look a lot like larvae. Their droppings look like a uniform powder made up of tiny granules the color of whatever they’ve been eating. They do not spin webs, nor make cocoons like the moths. They tend to burrow deep into carpets and may not always be obvious. As they mature, they shed their skins and then crawl from place to place. They are often found in areas that don’t provide food for them. Their fecal matter, however, is generally found where they’ve been eating. Both the larval and adult stages damage fabric and also feed on seeds, pet food and cereal products in your kitchen and pantry, as well as flowers in your garden. The adults measure 1/10” to 1/3” long. They’re oval shaped and vary in color from shiny black to various patterns of white, yellow, brown and orange.
Silverfish (Lapisma saccharina)
Silverfish are small wingless insects that do not have larvae in their life cycle. They lay eggs which hatch into nymphs that look like miniature adults. They molt several times as they grow, leaving their cast skins to detect. Both adults and nymphs damage fabrics. They love moisture (75 to 97% humidity), cool to moderate temperatures (70 to 80° at the most), and dark places. They tend to be most active at night, and feed on starch, sugars and proteins. You’ll find them in sinks and bathtubs because they enter looking for the moisture and then get trapped, unable to climb the slick, vertical walls. They also love rayon and the glue found in book bindings and wall paper. The presence of silverfish indicates a moisture problem, but they can survive long periods of dry conditions and starvation. Infested areas should be aired out and dried. They live for quite a long time compared to the moths and carpet beetles, sometimes as long as 5 to 7 years, but they are also not very prolific. A female will only lay about 20 eggs in her lifetime, depositing them in tiny cracks and crevices. The eggs hatch in 19 to 43 days and mature from hatching to adult in 3 to 4 months. The droppings of silverfish look like very fine black pellets, somewhat like miniature mouse droppings, scattered over the surfaces in dark areas where they reside. They may leave yellow stains, especially on linens.
Why Insect Damage Happens
Clothes are usually stored in dark, warm places. Insects and their larvae have a wonderful opportunity to feed undisturbed. The amount of damage that occurs is in direct proportion to the temperature and humidity in the storage area. Warm, moist areas are the ideal growing condition for insects!
Most damage occurs during the larval stage of the insect’s growth. That is also when they need the most food. The adults naturally gravitate to areas of your house that contain everything they need: a food source consisting of fabrics with remnants of stains or soil, warmth, and moisture. Examples of poor areas to store clothes: closets with exterior walls, garages or basements with concrete floors, and nice warm attics.
Continued in Part Three — Inspection and Elimination