ARTHROPOD MUSEUM NOTES
Number 55 • August 3, 2007 • Jeffrey K. Barnes
Foreign grain beetle
Genus and species: Ahasverus advena (Waltl)
Foreign grain beetles are brown and tiny, only about 1/16 of an inch long. They have two conspicuous and diagnostic round lobes on the prothorax right behind the eyes. The antennae have distinct, three-segmented apical clubs. The species gets its common name from the fact that the beetles are attracted to moist grain, where they feed on fungi. The beetles are also found in association with a wide range of moldy foodstuffs, including cocoa, oilseeds, dried fruit, herbs, spices, and roots. The foreign grain beetle has a worldwide distribution, but it is most abundant in tropical and warm-temperate regions. It is often seen as a pest in brand new homes in Arkansas, usually in the heat and humidity of midsummer. After sheetrock is plastered, mold forms in the wall voids, and this provides a food source for the beetles. The beetles start appearing by hundreds in new homes, causing much consternation to the owners. After the wall voids are sufficiently dried out, the problem usually cures itself without need of pesticides.