There are tens of thousands of different kinds of moths found throughout the world, with a great many kinds living in North America. There really is no possible way the average person will be able to recognize all of those that manage to get into his home, but when a moth is found it may be tempting to blame it for other problems we have recently encountered. This often is the case with "clothes moths", which are actually fairly uncommon moths in North America, but which certainly do have the ability to cause damage to various things inside your home. Like many other kinds of insects these moth species are responsible for some of the recycling in nature, feeding on dead things to hasten their return to the soil as nutrients needed by new plants and animals.
There are two species of clothes moths in North America that are most commonly found, and these are the Webbing Clothes Moth (Tineola bisselliella) and the Case-making Clothes Moth (Tinea pellionella). There is a third species called the Tapestry Moth that is rarely encountered, as well as a few species of little moths closely related to the case-making clothes moth, and these pop up now and then in homes to add to the mystery. These are referred to with various common names, but most often as the Plaster Bagworm, and while they potentially could feed on fabrics like the normal clothes moths do they generally stick to other kinds of foods. More on these guys later.
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.
The use of cedar chests is NOT a guarantee that you will avoid clothes moths or carpet beetles. While fresh cedar may emit an odor strong enough to be slightly repellent to insect larvae, it is not a certain guarantee, and over time the wood ages and fewer vapors are given off. You could store your susceptible clothing in a sealed container with moth balls or moth crystals in it, but this is not advisable. These products use either PDB or naphthalene, both of which are slight fumigants that can kill or repel insects when the insect is trapped in the container, but they also give off strong odors that can impregnate the fabrics, and your sweater or blanket will also give off that strong smell when you use them again. Moth balls are insecticides, and even could be harmful to people if too much of the vapor were inhaled.
You will also be subjected to advertisements for various electric repelling devices, such as ultrasonic repelling boxes, devices that plug into electric outlets to cause electromagnetic repelling waves, etc. While this quick-and-easy remedy may seem tempting it is better to save your money. Numerous unbiased university tests have been conducted on such devices, and the consistent conclusion is that they do no good whatsoever in repelling insects, rodents, or any other "vermin". The EPA and FTC regularly require manufacturers of these devices to stop their sale for lack of proof that they work, and one respected researcher from Texas A&M University states that insects are incapable of detecting ultrasonic sound, and thus should not be expected to be repelled by such magic boxes.
If you suspect or determine that you have clothes moths, it does not pay to focus on the adult moths, although killing them will certainly prevent them from laying more eggs. It also is likely that the moths will be active near to where they developed as larvae. What you need to find is the items in the home that the larvae are infesting, and deal with them appropriately. If there has already been substantial damage to the items it may be that placing them inside plastic bags and disposing of them is most appropriate. If the damage is slight then cleaning or laundering the items will remove or kill the larvae. Since we rarely have actual wool rugs in our homes anymore it is unusual for carpets to be infested. However, exotic rugs may be made from wool, and older carpets may have a waffle padding under them which could have wool threads in the matrix. Clothes moths have been found infesting this hidden resource.
Finding the infested materials can involve several tools, and one is simply your eyes and your knowledge of where you have placed items that may be subject to attack by fabric feeding insects. The adult moths may be more common in one room, and this can lead you to most thoroughly inspect that room. Perhaps you are finding the case-making larvae wandering around on the walls in a closet, and this is a definite sign that something nearby may be infested. It is even possible that a wild animal, such as a rat or a bird, has died in the attic or within a wall void, and these recyclers will eventually find that carcass and feed on the hair and feathers. You can purchase insect traps that use a pheromone, an odor highly attractive to clothes moth adults, and place these in a few places to see which traps draw the most insects, again narrowing your search for the infested materials. Some pest control companies may be able to sell these to you.
Pesticides play only a minor role in the control and elimination of clothes moths, and really would only be necessary if you had very, very large numbers of adult moths flying around the home, or if something like that carpet padding were infested and could not easily be washed. However, even in the rare instance of infested carpet padding the best course of action would be to remove it and physically eliminate the larvae, possibly then contracting with a licensed pest management company to do any application of pesticide. These companies have a wide variety of products they can use, including many that are derived from natural sources such as plant extracts. You can find a pest management company in your area by using the PMP Finder on the home page of BugInfo.
One of your tools for elimination of clothes moths should be a vacuum cleaner, physically removing any larvae, their webbing, and their fecal pellets from that infested item. If it is clothing that can be laundered you should use hot water and detergent, and these should kill or remove any larvae and eggs. Some studies have shown that insects on fabrics are quickly killed at temperatures of only 130 degrees, so if it is appropriate to place the material in a hot dryer this will effectively kill the bugs on it. Clothing can be cleaned by a professional dry cleaner to also eliminate the eggs and larvae. Preventing new invasions of the moths in the future can be done by storage of susceptible materials in moth-tight enclosures.
When you see that moth in the house don't panic. Odds are pretty good that it just flew in from the outside. However, there also is a chance that it is a moth that is infesting food, or a moth infesting fabrics, and until you know what you are dealing with you will have difficulty controlling the problem. For most problems with clothes moths or food moths there is no reason to reach for the can of insecticide. Instead, make a search, find the infested materials, and dispose of them or deal with them appropriately to rid yourself of the problem.