Perhaps one reason that clothes moths are so badly misunderstood is because you have been subjected to so much misinformation about them, even in TV sit-coms and other forms of media. The adult moths do none of the feeding damage, and in fact do not feed at all once they have become that adult moth. Like all other kinds of moths these insects begin life as an egg, deposited by the adult female moth on some material that is suitable for the larva to eat. The egg hatches to a tiny caterpillar, and this stage immediately begins feeding, passing through several stages (or “instars”) on its way to becoming the adult insect. All of the feeding by the clothes moth is done in this larva stage, as it is only the larva which has the jaws needed for chewing things. How rapidly the larva is able to complete its growth and change to the pupa stage, and then ultimately emerge as the adult moth, varies widely. Studies have shown that the complete development of a clothes moth can be in as little as 40 days, but may take over 2 years. Exactly why the clothes moths delay their development may not be understood.
Another feature of the biology of clothes moths is that they are not attracted to lights. While most moths you might encounter around the outside of your home will come to lights at night, clothes moths are essentially repelled by light. They will not be found circling that lamp in your living room, will not be found resting next to lights on the walls, and if they are suddenly exposed to light will tend to run away and attempt to crawl under something to hide from the light. The larvae prefer darkness as well, staying within the folds of materials in darkened closets or storage boxes. The larva of the case-making clothes moth may leave the infested materials and wander about a room, but will be most likely to do so if the room remains darkened.
The adult moths of both species are very small, and with their wings spread as wide as they can be they still have only a one half inch wingspan or less. Their wings are very narrow, tan to a shiny golden color, and without any noticeable markings on them. If you used a strong magnifying glass you might notice that there are very long hairs forming a fringe along the bottom of the hind wing. These moths are difficult to identify as the adult moth, and even look very similar to other kinds of moths that may be of no consequence at all, or similar to one kind of moth that could be infesting your food. If you do find adult moths in your home, and are concerned about their importance, consider having a licensed pest management company take a look at them for identification.
It is the larvae of clothes moths that are very distinctive, and we’ll begin with the Case-making clothes moth, so named because the larva creates a silk tube for itself immediately after emerging from its egg. It then spends its entire life within this case, dragging it everywhere it goes, enlarging it as the larva itself grows, and eventually changing to the pupa within the silk case. When the adult moth finally emerges from that pupa it simply crawls out the open end of the case. The presence of these tiny cases, at the largest no more than 3/8 of an inch long, is a sure sign that you have caterpillars on some sort of material. The silk is combined with fibers of whatever it is that the larva is feeding on, helping to add color to it and to camouflage the case on the food material.
The Webbing clothes moth larva also uses silk, but instead of a tube to hide in it spins a cover over itself, tending to stay under that silk canopy as it feeds. Another sign that you have moth larvae feeding on household materials will be the presence of silk, as well as a lot of tiny fecal pellets mixed in with the silk in the area where they are feeding. This silk is one way to distinguish between the damage done by a moth and that from a carpet beetle, which will feed on many of the same things as the moths do. The food of clothes moths is potentially far more than just “clothes”. They will feed on most things that are of animal origin, such as feathers, hair, skins, or anything made of wool. They feed on fish meal, dead or living insects, fingernail clippings, shed skins of reptiles, milk products, and other odd substances. They may even get into stored foods, feeding on food products that have a grain origin to them, and one alternative food resource has been shown to be fungi and mushrooms. In animal byproducts there is a chemical called Keratin, and clothes moths and carpet beetles are some of the few insects able to actually digest this substance, making them “true” fabric pests.
The Plaster Bagworm, mentioned earlier as another kind of case-making moth, may also feed on fabrics like its cousin the Case-making Clothes Moth. However, more commonly they may be found feeding on various bits of detritus and debris found around the home, such as dead insects in window sills, spider webs, and other organic matter. Occasionally they may be found in large numbers feeding on the fungus that grows on wood, and perhaps could be a sign in the structure of water leaks or excessive moisture accumulating on wood. The larvae also create their silk case to live in, carrying it around with them, and as active larvae may be found resting on a wall or furniture. The case is similar to that of the case-making clothes moth, but the ends seem to be more tightly pinched and there often are tiny grains of sand or dirt incorporated into the case along with the silk. This moth species has undergone a number of changes in its scientific name, but at the moment a species found along the East Coast is called Phereoeca uterella, and a species found in the western states is Phereoeca allutella.
Given their long life cycles it often takes quite awhile for noticeable damage from clothes moth to occur, and it is materials that are left in storage for long periods that are most susceptible. Wool sweaters or blankets may be in closets or drawers, objects with feathers on them stored in boxes, or other things that just are not used often but are kept stored around the home. These insects are part of the recycling crews in nature, and it is their job to find these leftover materials and reduce them to usable nutrients again. Controlling clothes moths, therefore, can begin with proper storage and maintenance of your valuable fabrics. They can be placed within plastic garment bags or other sealable plastic bags that are then sealed airtight.