Description of warehouse beetles and cabinet beetles
Warehouse beetles (Trogoderma variable) and larger cabinet beetles (Trogoderma inclusum) are two of several household pests that are closely related to carpet beetles (Coleoptera: Dermestidae). Adults are typically 1/8 to 3/16-inch long, elongate oval in shape and brownish-black with variable patterns of transverse bands of pale yellow-to-off-white hairs on the back. Warehouse and cabinet beetle larvae are up to 1/4-inch long, narrow, tapered, and yellowish to dark brown, and hairy. Larvae are usually found within infested, stored items.
Damage caused by warehouse beetles and cabinet beetles
In the home carpet beetles are pests of stored woolen clothing or wool carpeting. Cabinet and warehouse beetles, on the other hand, are more likely to may be in grain products, cereals, seeds, candy, dried fruits, nuts, and pet foods. Both insects will feed on animal-origin products including woolen clothing, dried milk and dead insects, including dead flies, boxelder bugs, and ladybugs in wall voids and attics.
Management of warehouse beetles and cabinet beetles
Control of cabinet and warehouse beetles requires locating and eliminating infested items (clothing, food products, etc.). Often, the source may be difficult to find or there may not be a single source. Carefully examine all susceptible foods and throw away foods that are infested. Check accessible places where dead insects may accumulate. Thoroughly vacuum clean cabinets and shelves to pick up crawling insects and spilled or infested material. Washing shelves with detergent, bleach, ammonia or disinfectants will not have any effect on stored product insect pests.
Insecticide sprays are not recommended in food storage areas. Sprays have no effect on insects that are within packages. If beetles are found throughout the house, localized applications of residual insecticides may be warranted. Lightly spray cracks, corners and edges where insects are likely to crawl. Ready-to-use residual insecticide products such as "ant and roach killers" are appropriate for this purpose. See this article for more on insecticides. Cases of heavy, widespread infestation may require the services of a professional pest control operator.
Do you live in Iowa and have an insect you would like identified?
The Iowa State University Plant & Insect Diagnostic Clinic will identify your insect, provide information on what it eats, life cycle, and if it is a pest the best ways to manage them. Please see our website for current forms, fees, and instructions on preserving and mailing insects.
Contact information for each states diagnostic laboratory for U.S. residents. If you live outside of Iowa please do not submit a sample without contacting the Plant & Insect Diagnostic Clinic.