Insect Of The Month
Beetles Infesting Woolens
Injury. Furnishings and clothing made of wool, and of fur, feathers or hair, are subject to damage by insects. The most serious insect pests of such articles are beetles known collectively as carpet beetles. Damage may range from the clipping of an occasional fiber, which only slightly weakens the fabric and may go entirely unnoticed, to the total destruction of articles left undisturbed for many months or years. Fabrics made of a combination of wool with synthetic fibers are not immune to damage.
Actual feeding upon wool fiber is done only by the beetle larvae, the presence of adult beetles is simply an indication of an infestation in the dwelling and that woolens should be inspected. The adult beetles themselves usually feed out of doors upon the pollen of flowers.
The feeding of carpet beetle larvae can be differentiated from the feeding of clothes moths by the fact that no tell-tale web is spun by the beetles. Where carpet beetle feeding is light, damage may therefore go unnoticed, or the fabric may ravel when only a single thread has been severed.
Description. There are a few
different kinds of carpet beetles that attack woolens. The most frequently encountered
carpet beetle in New York State is the black carpet beetle, Attagenus megatoma.
The adult beetle is dull black in color, antennae and legs are brown, and it
is elliptical in outline, about 1/4 inch long. The larva, on the other hand,
may grow to a length of 1/2 inch before entering the pupal stage. The larva
is somewhat carrot-shaped, and bears a tail of long brown hairs. Its body is
covered with golden brown hair only slightly lighter in color than the tail.
Two other species of carpet beetles are commonly found in homes in New York.
They are the carpet beetle Anthrenus scrophulariae, sometimes called the common
or old fashioned carpet beetle, and the furniture carpet beetle, Anthrenus flavipes.
These two species are very difficult to tell apart, for their appearance and
habits are quite similar. Both larvae and adults of these species are somewhat
shorter and more robust in general appearance than the black carpet beetle.
The larvae may be no more than 1/4 inch long when full grown, and they are covered
with rather long dark brown hairs. These features lead to the use of the term
"buffalo moth" in referring to the larvae. Adults are less than 1/4
inch in length, and present a mottled appearance due to scales of dull white,
yellow, dark gray and reddish-brown color occurring in a diffuse pattern.
Life cycle and habits. In areas of the home where temperatures are held at a comfortably warm level throughout the year, carpet beetles develop in an uninterrupted cycle. When woolens are stored in an unheated portion of the house, development slows or stops during the winter months, the insects passing the colder season as larvae. In the spring, as temperatures rise, the pupal stage occurs. The insects are inactive during this period of transformation, which may last for 1 to 4 weeks. Then, adult beetles emerge, lay eggs on a fiber appropriate for larval feeding, and seek the out-of-doors and flowers upon whose pollen they feed.
Fifty eggs or more may be deposited
by a single female. In 7-14 days the eggs hatch and the larvae begin their destructive
feeding. They avoid light during this period of growth, pausing on occasion
to shed their skins as they develop. Sixty days to nearly a year may be spent
in this destructive form, depending upon conditions of
food and temperature. The pupal stage again occurs, and with the emergence of
the adult, the life cycle is completed. Thus, as many as four generations or
as few as one may be passed in a year.
Management. Sources of infestation. The list of materials upon which carpet beetles can feed successfully is extensive. It includes such diverse substances as meal and flour, peas and beans, animal dandruff, dead insects, leather, dried meats, silk, powdered milk and dog food as well as the natural food substance of wool, fur, hair and feathers mentioned previously. Eggs, larvae, pupae and adults may be brought into the home in any of these substances. Before the infestation is discovered, the active forms (larvae and adults) may have distributed themselves in such places as the lint collected behind baseboards, in air ducts, in the stuffing of furniture and in the bristles of old paint brushes. From these unsuspected locations, carpet beetles may continue to reinfest valued woolens for long periods of time.
Damage by carpet beetles can
best be prevented by housekeeping practices which prevent the establishment
of an infestation. Regular vacuum cleaning of carpets, with careful attention
to areas beneath low and heavy furniture is important. Likewise, bare floors
where lint may accumulate in cracks should be cleaned, and furnace air ducts
should be kept lint and dust free insofar as possible. The relatively regular
brushings and frequent use of woolens tend to expose and kill eggs, larvae and
pupae before damaging numbers accumulate.
Mothproofing in the manufacture of woolens is of great value, and may last for
the life of the product. Treatments applied by dry cleaners are often less permanent
and must be renewed regularly.
Stored woolens should be placed in containers which can be sealed tightly, for
small larvae can enter through very small openings. Most closets and trunks
are not adequate to protect woolens for long periods of time.
The use of moth crystals (paradichlorobenzene and napthalene) can be misleading. These substances serve only as repellents against adult carpet beetles. If eggs or larvae are present, damage may be extensive even in the presence of the vapors of these chemicals.
The insecticide tetramethrin may be used as a spray on woolens as a temporary measure to prevent or control an infestation. To avoid fabric damage, be sure to test on a small area first. Diazinon or tetramethrin may also be used in infested areas. If a dwelling is found to be extensively infested, treatment by a qualified professional pest control expert may be necessary.
11/1972 Prepared by Edgar M. Raffensperger and Carolyn Klass Dept. of Entomology Senior Extension Associate, Cornell 1/1989 Slightly revised