The drugstore beetle and the closely related cigarette beetle are small reddish-brown beetles that infest grains, pet food, straw flowers, tea, old rodent bait, red pepper, flour, spices, leather, animal hair, tobacco and other dried plant material. Historically, these insects were often pests of herbal medicines and pharmaceuticals, thus their common name. Drugstore beetles are brought into the home on food items, and often spread to other products before an infestation is discovered.
Life cycle: The life cycle of the drugstore beetle takes three to four months at room temperatures. Small C-shaped grubs can be found feeding inside infested products. Adults are 1∕8 to 1∕10 inch long and cylindrical. Infested products often have small round “shot holes” in packaging and large amounts of dusty frass (insect waste) inside. Holes and damage found in packaging are caused by the adults as they leave the product. Drug store beetles are unusual for grain pests because the adults can fly and often collect near lights and windows. Adults can often be found a good distance from the source, which makes locating the source of the infestation difficult.
Control: Because drugstore beetles are food pests, the best control is to clean up and dispose of infested products. Check all potential products for activity. Uninfested dry goods should be stored in sturdy glass or plastic containers with tight fitting lids to prevent spread of the infestation. Heating infested products to 140oF for two to three hours or freezing at 20oF or less for 48 hours will kill all life stages. You cannot control this pest with insecticides because you cannot spray the food source. The number of beetles should drop within one to two weeks of the clean-up. If beetle numbers remain high, look for other sources of the problem within the home.
For more information on drugstore beetles: Contact your county Extension agent.
© 2019 the Board of Regents of the University of Wisconsin System doing business as University of Wisconsin-Madison Division of Extension.
An EEO/Affirmative Action employer, University of Wisconsin-Madison Division of Extension provides equal opportunities in employment and programming, including Title IX and ADA requirements. This document can be provided in an alternative format by calling Brian Hudelson at (608) 262-2863 (711 for Wisconsin Relay).
Thanks to Karen Delahaut and Susan Mahr for reviewing this document.
A complete inventory of University of Wisconsin Garden/Farm Facts/Pest Alerts is available at the University of Wisconsin-Madison Division of Extension Plant Disease Diagnostics Clinic website: https://pddc.wisc.edu.