Apr 9, 2011 – Material Munchers
QUESTION:
What is the main difference between all household fabric pests? What are the control measures?
ANSWER:
If we consider only the "true" fabric pests, meaning those insects that actually are able to consume and digest fabrics, then we have a fairly small crowd. This includes carpet beetles of various kinds, including the typical Dermestes, which are the black, white, and tan kinds, as well as Trogoderma, which are the brown and black ones called "warehouse" beetles. It also includes the Black Carpet Beetle. All of these beetles may also feed readily on grain-based food materials, so their presence in a home does not necessarily indicate that animal-based fibers are under attack. Animal products such as hair, feathers, or skin will contain a chemical called keratin, and very few insects are able to digest keratin. But, Mother Nature needed all of these materials decomposed and recycled when animals died, so the carpet beetles (Dermestidae) and clothes moths stepped in to fill that role.
The other group of true fabric pests is the moths, and these "clothes" moths include the webbing clothes moth, whose larva creates a tunnel or covering of silk over itself on the material it is feeding on, and the case-making species, which create a small tube or "case" of silk that they then live in and drag everywhere with them. There actually are 3 kinds of case-making moths found in homes, with the Casemaking Clothes Moth probably the most common. Its case is camouflaged with bits of material from the fabric it feeds on incorporated into its silk case. There also are the Household Casebearer Moth and the Plaster Bagworm, which make similar cases around themselves as larvae, but which may be more inclined to feed on other things, such as spider webs or fungus. But, they also may feed on fabrics, so their presence is cause for suspicion. When you compare the cases of these 3 species you see some obvious differences. The Household Casebearer often has a very dark case, perhaps due to the incorporation of dark wood or molds into its silk. The Plaster Bagworm case has a grainy look due to the use of sand imbedded in its case.
All of these case making moths will stay within their case for the duration of their larval stage, pupate within it, and then emerge as the adult moth. They drag the case everywhere with them. All of the adult moths are very small and pretty nondescript, although again you can find some basic characters that may identify each of them, including spots on the wings or patches of hair on top of their head. The carpet beetles are pretty obvious, and the larvae of all of them are distinctive as small, brown, very hairy and active larvae. The differences are in the lengths of the hairs sticking out their posterior end, the body shape, and the pattern of darker rings around the body. Without going into all the details here I'd invite you to check out our Pest ID resource on PestWeb, where all of these kinds and images of them are available.
Control of fabric pests is much the same principle as control of food pests - it is imperative that you search until you find the source, meaning the material that is infested. This will nearly always be in some hidden location, and spraying pesticides around the general area is just not going to get to the larvae that are feeding and doing the damage. You may kill adult insects that are out and about, but they will quickly be replaced by new adults emerging from the infested product. If it is infested fabrics you may well not even want to spray, since it could be sweaters or blankets where a pesticide is not appropriate. In that case laundering or dry cleaning will kill the insects, vacuuming will remove others in the general area, and at that point perhaps a directed application of insecticide to kill wandering larvae that are not easily observed.
There are pheromone traps for the beetles and the moths, and these can be used as monitors to determine if these insects are present in a sensitive situation, such as a museum, or they can help narrow the search for the source, by placing many of them and then determining which ones have the insects in them, or the most adult insects indicating those may be closest to the problem area.
What is the main difference between all household fabric pests? What are the control measures?
ANSWER:
If we consider only the "true" fabric pests, meaning those insects that actually are able to consume and digest fabrics, then we have a fairly small crowd. This includes carpet beetles of various kinds, including the typical Dermestes, which are the black, white, and tan kinds, as well as Trogoderma, which are the brown and black ones called "warehouse" beetles. It also includes the Black Carpet Beetle. All of these beetles may also feed readily on grain-based food materials, so their presence in a home does not necessarily indicate that animal-based fibers are under attack. Animal products such as hair, feathers, or skin will contain a chemical called keratin, and very few insects are able to digest keratin. But, Mother Nature needed all of these materials decomposed and recycled when animals died, so the carpet beetles (Dermestidae) and clothes moths stepped in to fill that role.
The other group of true fabric pests is the moths, and these "clothes" moths include the webbing clothes moth, whose larva creates a tunnel or covering of silk over itself on the material it is feeding on, and the case-making species, which create a small tube or "case" of silk that they then live in and drag everywhere with them. There actually are 3 kinds of case-making moths found in homes, with the Casemaking Clothes Moth probably the most common. Its case is camouflaged with bits of material from the fabric it feeds on incorporated into its silk case. There also are the Household Casebearer Moth and the Plaster Bagworm, which make similar cases around themselves as larvae, but which may be more inclined to feed on other things, such as spider webs or fungus. But, they also may feed on fabrics, so their presence is cause for suspicion. When you compare the cases of these 3 species you see some obvious differences. The Household Casebearer often has a very dark case, perhaps due to the incorporation of dark wood or molds into its silk. The Plaster Bagworm case has a grainy look due to the use of sand imbedded in its case.
All of these case making moths will stay within their case for the duration of their larval stage, pupate within it, and then emerge as the adult moth. They drag the case everywhere with them. All of the adult moths are very small and pretty nondescript, although again you can find some basic characters that may identify each of them, including spots on the wings or patches of hair on top of their head. The carpet beetles are pretty obvious, and the larvae of all of them are distinctive as small, brown, very hairy and active larvae. The differences are in the lengths of the hairs sticking out their posterior end, the body shape, and the pattern of darker rings around the body. Without going into all the details here I'd invite you to check out our Pest ID resource on PestWeb, where all of these kinds and images of them are available.
Control of fabric pests is much the same principle as control of food pests - it is imperative that you search until you find the source, meaning the material that is infested. This will nearly always be in some hidden location, and spraying pesticides around the general area is just not going to get to the larvae that are feeding and doing the damage. You may kill adult insects that are out and about, but they will quickly be replaced by new adults emerging from the infested product. If it is infested fabrics you may well not even want to spray, since it could be sweaters or blankets where a pesticide is not appropriate. In that case laundering or dry cleaning will kill the insects, vacuuming will remove others in the general area, and at that point perhaps a directed application of insecticide to kill wandering larvae that are not easily observed.
There are pheromone traps for the beetles and the moths, and these can be used as monitors to determine if these insects are present in a sensitive situation, such as a museum, or they can help narrow the search for the source, by placing many of them and then determining which ones have the insects in them, or the most adult insects indicating those may be closest to the problem area.
