Based on specimens received for identification, drugstore beetles must be the most common stored product pests in Kentucky homes. They can chew into unopened paper or cardboard boxes, as well as cellophane, plastic, and foil wrapped packages. Once inside, numbers build up in just a few weeks, often spreading to other stored foods and into food debris accumulated in cupboard corners, cracks, and crevices. These insects contaminate more food than they consume. Infestations usually are discovered when adults leave the infested food to crawl about the house.
Female drugstore beetles lay their eggs on many types of stored products. The tiny grub-like larvae that hatch from these eggs can enter packaged products through very small cracks and openings. Development from egg to adult can take 3 to 4 months.
The key to eliminating stored product insects is to find and destroy infested products and breeding sites. They will always be associated with food-based materials, but they also can live in food that has accumulated in cracks and crevices of shelving. Examine boxes and bags of processed foods, such as meals and mixes, for tiny holes in the packages. Look inside opened containers for signs of infestation.
Here are some of the items that fit the drugstore beetle’s diet: flour, dry mixes, chocolate, spices, dried herbs, cookies, stored grains, dried fruits and vegetables, wool, leather, horns, hides, books, and even wood. How can it be so small (about 1/8 inch long), yet be able to eat almost anything? Drugstore beetles have symbiotic yeasts that help them digest a very wide range of foods. Finding and discarding infested items is the key to eliminating infestations. There are many places to look!
Managing an Existing Infestation
- Remove all food from storage areas and discard infested materials.
- Use a strong suction vacuum cleaner with crevice attachment to clean shelves and in cracks and crevices. If shelving is removable, clean all surfaces, including backs, where insects or small amounts of food can be overlooked.
- Look around bottom lips of cans and other containers for hiding beetles, which can be wiped up with soapy water and discarded.
- Check packaging dates when buying products.
- Do not buy products in damaged packages.
- Purchase seldom-used foods in small amounts and store in sealed containers. Store these items in a refrigerator or freezer if you can.
- Mark the purchase date on packages so the oldest items can be used first.
- Promptly clean up spilled flour, mixes, crumbs, etc. and thoroughly vacuum and clean areas where contaminated items were stored.
- Store foods in airtight glass, metal, or plastic containers.
- Clear containers make it easier to check for infestation.
By Lee Townsend, Extension Entomologist