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Two types of insects are responsible for damage to wool clothing, wall hangings, feathers, silk garments, felt, furs, wool rugs and carpeting. In Wisconsin there are two species of clothes moths and several species of carpet beetles that attack natural fibers. Most damage is done during storage because these insects are most active in dark, undisturbed areas.
Carpet beetles are responsible for 80% or more of the woolen damage we see in the Insect Diagnostic lab. Every home has some carpet beetles and they commonly breed outdoors in Wisconsin. Carpet beetles can be found in most bird and wasp nest, and in attics, closet floors, along baseboards, in heating ducts and cold air returns, inside wall voids and in furniture and appliances where they feed on dead insects, animal hair, dead animals (mice or birds), food crumbs, pet food, seeds, spices, household lint and some dry goods. They will feed on wool, silk, furs, and any clothing soiled with blood, urine, beer or food stains.
The damaging stage are small, brown, bristly or hairy, slow moving, segmented larvae that are 1/5 inch or less in length. An average life cycle takes one year but can vary from 4-36 months. Larvae can grow backwards (called retrogressive molting),if deprived of food. This adaptation allows carpet beetles to live for months without food. Adults are not damaging and feed on flower pollen. Females lay fragile eggs singly near food sources that hatch within 2-3 weeks.
Feeding damage appears as small irregular holes. Fabric strands are clean cut with little associated debri, dust or and webbing . You can sometimes find the brown, cast larval skins nearby. Damage will be common on undersides of wall hangings, beneath furniture, in unvacummed closets, and on the underside of folded clothing stored on the floor or shelving.
Casemaking (Tinea pellionella) and webbing clothes moth (Tineola bisselliella) numbers have increased in recent years due to the dramatic increase in infested imported, woolens and Oriental carpets. Adults are small 1/3 inch yellowish tan to buff colored moths that rarely come out into lighted areas. The damaging stage is small white caterpillars with dark heads. The casemaking clothes moth caterpillar spins a protective cigar like case from silk and material fibers. Damaged areas appear as small holes that have webbing, debri covered cocoons and small pellets mixed in.
If large numbers of fabric pests are seen, search for a hot spot as the source. Infested wallhangings, pet food, wasp nests, wool yarn stored under bed frames, furs, or accumulations of dead insects material. Other sources include old furniture with horse- hair padding, and homes built during the 1920 and 30's that commonly used animal hair mixed with plaster.
Prevention is easy when storing articles in tight fitting garment bags or plastic storage containers. All garments should be cleaned before storage. Consider using plastic or zip lock bags to store sweaters in dressers. Storage cartons can be sealed with good quality tape, All seams and joints should be taped over. Vacuum closet floors, shelves and dresser drawers before putting clothing away for the summer. Furs can be professionally cleaned and place in cold storage for protection.
Good housekeeping will remove, lint, dust, or hair . Be sure to move and vacuum under furniture if you have wool rugs, and the 1/2 inch space along baseboards that is missed by many vacuums . Areas that are frequently vacuumed do not become damaged., behind heaters, and in.
Cedar oil, cedar chips and cedar closets have generally been overrated as a control of wool pests. Very young larvae of clothes moths that are exposed to high concentrations of cedar oil vapor are killed, but older larvae, adults and most carpet beetles are not affected by the oil. Cedar lumber in closets or chests will lose oils over time and after 3 years are useless in killing any fabric pest. The advantage of tight fitting, well constructed cedar chest is that it make it difficult for insects to get to the clothing.
If you have found a problem, vacuum or brush the insects off the article. Washing or dry cleaning will kill all life stages. Freezing is an option if the article has been kept at room temperature before the treatment. Place articles in freeze or in plastic bags, (with air removed and loosely packed,) expose to below zero for 72 hrs. Clothes moths and carpet beetles can survive in unheated attics, bird nests, wall voids and other sites if they have a chance to acclimate to slowly falling temperatures. The shock of going from 70 to near 0 is what kills the insects. Heating articles above 130o F for 1 hrs will also kill all life stages.
Direct spaying of fabric with insecticides or moth proofing agents is always a risk because of staining, discoloration, shrinkage weakening fabrics , and other chemical reactions caused by water, solvents or the chemical themselves. These chemicals are also difficult to find. There are clothing sprays that contain pyrethrum, permethrin, allethrin or resmethrin. A wider selection of insecticides are registered for carpet treatment but the same care is needed.
Moth balls (naphthalene) and PDB (paradiclorobenzene) change into gases and work as fumigants, but are ineffective as repellents . To be effective, they must be confined in a closed system with little air movement such as a sealed plastic box. Hanging these products in a closet will usually not build up to toxic levels, or if they do there is concern if people are breathing that much vapors. Clothing will need to be aired before use.
January 1996
