Lesser Grain Borer
Possibly originating in the West Indies where it is believed to have fed on trees and their roots, this beetle is now found worldwide. Most other members of the family have larvae that are wood feeders, including several that are destructive to structural wood members and furniture.
Eggs are laid on the outside of the food material, including whole grains such as corn, wheat, rice, or other grains, and the larvae bore through to feed within the grain. It is a pest primarily of grains and hard foods such as pet foods and pasta. The eggs are laid in small batches of 2 to 30 at a time, the larval development takes around 2 months under most conditions, and adults live only a few months. Both larvae and adults feed on the stored food materials, and their jaws are strong enough that they will bore into other materials such as wooden crates or shelving near the food product.
This beetle is one of the smallest of the stored food pests, resembling a small piece of broken off, thin pencil lead. It is dark brown to black, less than 2 mm long, and is cylindrical. The antennae are composed of a series of very short segments followed by 3 enlarged, serrate segments at the end. When viewed from above the head is hidden under the overhanging prothorax, and good magnification will show a series of raised, rough ridges across the top of the prothorax.
Characteristics Important in Control:
Prevention of the pest by good storage practices and proper stock rotation is important. Fumigation with methyl bromide or aluminum phosphide may be needed to kill existing larvae already within the grains, and disposal of infested material may be necessary.