The Drugstore Beetle Thrives on Poison
By Chris Williams on January 25, 2017.
My daughter said she learned in her science class about a little beetle that feeds on prescription drugs and even eats things like strychnine. I know insects do strange things but is that really true? R. W., Alton, NH
It is true. I’m sure that the beetle you’re talking about is the drugstore beetle, Stegobium paniceum. Here’s how it got its name. Back in the day when apothecaries or pharmacies stored dried herbs and powdered drugs in bulk and doled them for customers as needed, drugstore beetles were serious pests. In those days, most “curatives” were derived from plants. Drugstore beetles have even been known to feed on laxative teas and poisonous substances such as strychnine and belladonna. These beetles are occasional pests in homes today, not because they are feeding on drugs but because they are also what we call stored food pests.
Drugstore Beetles Used to Be Pharmacy Pests
The drugstore beetle larva is a whitish C-shaped grub (about 1/6-inch long) with a darker head and legs and causes all of the feeding damage. The beetle larvae will feed on a variety of foods including spices, herbs, cereal, flour, nuts, pasta, seeds, dry pet food, dried fruit, coffee beans, and just about anything in between. Like most stored food pests, they usually infest foods that are old, moldy, or past their expiration date. The larvae are known for chewing entry or exit holes into even sealed food packages. Drugstore beetle larvae have been known to also damage books, wood, fabrics, leather, horns, tin, and lead, usually when they bore in looking for a protected place to pupate.
The Cigarette Beetle is a Close Relative
The drugstore beetle adult is reddish-brown, oval, and only about 1/10-inch long. Its head is bent downward, giving it a humpbacked appearance. It flies to lights and can be found around windows or flying in circles over a food source. The drugstore beetle looks like and is very closely related to the cigarette beetle which seems to get more attention. In the olden days, the cigarette beetle, as it name implies, infested stored tobacco and tobacco products. Today, both beetles are primarily pests of stored and packaged foods (see Tiny Cigarette Beetles Infest Many Food Products).