Although its name is drugstore beetle, this insect is a general feeder that attacks everything edible and many things people would consider inedible. The drugstore beetle got this common name because it was often found feeding on drugs in pharmacies. In households they attack a wide variety of foods including flour, meal, breakfast food, pepper, spices, seeds, pet food, cereals, raisins, pasta, chocolate, ginger, bread, and rubbed parsley for seasoning. Dry dog food is one item frequently infested by the drugstore beetle. In a library, they may destroy books and manuscripts. In other places, they even feed on poisonous materials such as strychnine, belladonna, and wheat poisoned with strychnine. To prevent drugstore beetle attacks or to control their infestations, it is important to know what they look like, how they live, and where to find them.
The adult drugstore beetle is cylindrical in shape, 1/10 inch (2.5 mm) in length, uniformly brown in color and covered by fine silky dense hairs. The head is not visible from above, giving a humpbacked appearance when seen from the side. Their antennae have three enlarged segments at the end. There are some rows of deep pits on their wing covers. Their eggs are pearly white and are not easily seen with the naked eye. Drugstore beetle larvae are C-shaped (grub-like), about 3/16 inch long, and creamy white in color.
Life Cycle and Habits
Female drugstore beetles lay eggs singly in suitable foodstuff. They lay between 23-114 eggs that hatch in 9 days. The larval (immature) period is up to 57 days. At the end of the larval stage, they form a little round ball or cell, which becomes their cocoon. This stage lasts from 12-18 days. The complete life cycle takes about 75 days depending on conditions. Adults can fly and are attracted to light.
Prevention and Control
Good sanitation is the best prevention and control for drugstore beetle infestations. If you follow a few recommendations you can usually eliminate the problem quickly.
- Only purchase food packages that are sealed and show no sign of insect damage.
- Only purchase food in amounts you can use in a short period of time (between 2 to 4 months), especially during the warm summer months. At home, “rotate stock” just the way most stores do. Use older packages before new ones and opened packages before unopened ones.
- Store all foods in insect-proof containers with tight fitting lids or freeze them in 0o F. Freezing grain products for 3 days after purchase is a good habit.
- Keep cabinets and the surrounding area clean and free from food spillage. Vacuum all dust and debris from cabinets and floor of the kitchen. Do not clean cabinet with water because this may leave a pasty residue attractive to the pest.
- Properly ventilate the storage area to discourage these moisture-loving pests.
- Identifying all infested food and discard or treat (by freezing) them. Inspect packages of birdseed, grass seeds, and dry pet food. Infestations sometimes originate from birdseed or pet food stashed away by mice in an attic or behind wall. Don’t forget to inspect your bookcases; the drugstore beetle has even been known to nibble on books.
Avoid using insecticides around food. Use them only as a last resort and carefully follow the label directions. If you decide to use insecticides, choose a household insecticide labeled for pantry pests. Remove all food and clean cabinets. Discard all infested food. Do not treat surfaces used for food storage, preparation or where kitchen appliances or utensils are kept. Give special attention to cracks and crevices in cabinets. Allow the insecticide to dry before returning food to cabinets. Cover the shelves with clean shelf paper. After treatment, good sanitation and proper storage are keys to preventing future infestations.
Originally published 02/01