Drugstore Beetle

The drugstore beetle, Stegobium paniceum (L.), is a pest of stored products. The scientific name, paniceum, comes from the Latin word for bread. Some people suspect that the drugstore beetle’s common name came from its tendency to infest the herbs that early druggists used as medicine.

The drugstore beetle infests most food materials, including flour, cereal, and spices. It also infests many non-food products, including books and manuscripts, fur, leather, and horn. Drugstore beetles have even been found in products that are poisonous like strychnine. Because they can infest such a variety of materials, these beetles can become a problem in more than one part of a home.

The drugstore beetle is a small insect. The adult is about 1/10” long. It is oval-shaped and brown in color. Viewed from above, the head is not visible, so the beetle appears to be “humped”. The wing covers are lined with parallel rows of deep pits or punctures. The adult beetles can fly and they are attracted to light.

The adult beetle lays eggs on the food. When the larva hatches, it eats and grows. The larva stage lasts for several months. The full-grown larva spins a silken cocoon. Inside the cocoon, it takes more than two weeks for the larva to change to an adult. In a warm climate, the beetles can produce as many as four generations per year.

Homeowners often discover adult beetles in the pantry of near the kitchen windows. Controlling drugstore beetles begins with a thorough inspection. It is important to find everything that the beetles have infested.

In the kitchen, throw away any infested food. Clean pantry and cabinet shelves with a vacuum. Insecticide application is the final step. It should be applied only in cracks and crevices. The object is to help eliminate any beetles that may be hiding without contaminating surfaces. Incomplete treatment can allow survivors to re-infest. It is advisable to call a pest control professional to do these treatments.

It can be difficult to find infestations in other parts of the home. A flashlight will help with the inspection.

There may be infested materials that are too sensitive for insecticides. Heating the item (140° – 176°) for several hours will kill all stages of the beetles. In warm weather, heat-treat bulky items by wrapping them in black plastic bags.  Place them outside in the sun for several hours.