Description of redhorned grain beetles
The redhorned grain beetle is a moderately common, fungus-eating beetle found throughout Iowa. Though they are not commonly noticed, they are abundant in the fall and the early spring. When redhorned grain beetles are noticed, it is usually in the house where they have wandered in by mistake as accidental invaders. Others may be carried in by accident with firewood or other items.
Redhorned grain beetles are about 1/4 inch long and velvety black with a purplish tinge. The "redhorned" name refers to their reddish-yellow antennae. As the name implies, redhorned grain beetles are found in grain, especially stored ear corn. However, they do not attack clean, sound grain but instead are found in grain that is damp, moldy and out-of-condition. They are also common in other fleshy fungi such as wood decay fungi found under loose bark of logs and firewood. This beetle apparently has one generation per year.
Management of redhorned grain beetles
Redhorned grain beetles are harmless. They do not bite or sting and will not attack people, pets, furniture, the house structure or plants. They are merely a nuisance by their presence. Beetles inside the house need only be vacuumed or picked up and discarded. Preventing the beetles from getting into the house will require locating the source of the beetles. I hope the comments above make this search easier.
Redhorned grain beetles in stored grain should be treated the same as other grain-infesting pests using fumigation or grain protectants as warranted. Special attention should be given to cleaning spills and damp, moldy grain accumulations.