Spider beetles are rarely seen by people because they are active mainly at night or are hiding in dark, unnoticeable areas. They prefer to feed on cereal and cereal products like wheat, barley, and rye; they like to feed on food that is moldy or old and unusable. Spider beetle are scavengers and also feed on feces and other dead insects.
Along with contaminating food sources, when the larvae bore holes into wood in homes and other buildings in order to pupate they leave behind noticeable scarring. These stored product pests are problematic in homes, but cause much more of an issue in large food storage warehouses.