ARTHROPOD MUSEUM NOTES
Number 50 • July 30, 2007 • Jeffrey K. Barnes
Genus and species: Stegobium paniceum (Linnaeus)
The drugstore beetle has a worldwide distribution, and it is one of the most common household pests in Arkansas. The larvae, small white grubs that are rarely seen, can extensively damage a wide variety of plant and animal materials stored in the home, but they most commonly infest dry foodstuffs, such as pasta, bread, crackers, cereal, pet food, spices, flour, sauce mixes, dried fruit, dried fish, and fish meal. Dried flower arrangements are a source of infestation as well. In parts of the world other than North America, this species is also known as the bread beetle or biscuit beetle. The North American common name is derived from the beetles' habit of feeding on prescription drugs.
Drugstore beetles are common and serious pests in commercial food processing plants and distribution centers and in museums. They often feed externally on grains, but they can devour the inner portions as well. In museums, they can be found destroying botanical specimens, seeds, spices, stored foods, books, leather, cork, insect specimens, and mummies. The beetles have been known to bore a line through a whole shelf of books.
Drugstore beetle adults average about 2.5–3.0 mm long and are uniformly brown with grooved or striated wing covers. The antennae bear an apical 3-segmented club. The hood-like prothorax conceals the head when the beetle is viewed from above. Although larvae produce most of the feeding damage, the adult stage is usually the one first noticed when an infestation is at hand. Large numbers of dead beetles tend to accumulate at light – perhaps a night light in the bathroom, or near a window. Adults also can be detected flying about a darkened room in which a television is playing.
Once an infestation of drugstore beetles is noticed, sanitation becomes a priority. When the infested product is located, it should be contained and discarded. In homes, cupboards are the usual harborages. Boxes, bags, and even foil packets containing infested materials may have small escape holes bored through them, and a telltale dust of chewed foodstuff may appear on the floor of the cupboard. In warm, humid areas, where infestations are most common, grains, flour, and similar items can be stored in a freezer to prevent recurring infestations. Museum specimens can be heated to 125ºF for 2-4 hours or they can be given multiple exposures to -20ºF for two days.