Lesser Grain Borer

Lesser grain borers mainly attack wheat, corn, rice and millet. Both the larvae and adults are primary pests. They bore irregularly shaped holes into whole, undamaged kernels and the larvae (immature stages ), may develop inside the grain. Larval and adult feeding in and on grain kernels may leave only dust and thin brown shells. A sweet, musty odor is often associated with infestations of this insect.

The adults are 0.1 inch long, brown to black beetles with cylindrical bodies and numerous small pits on the wing covers. The head is directed downward and covered by the

pro-thorax so that is t is not visible when the insect is viewed from above.

The female deposits her eggs in clusters of 2 to about 30 on kernels. Most of the newly hatched larvae chew into kernels and complete their entire development there. However, the larvae can feed on fines or can develop as free-living insects in the grain. There are four larval stages. Development from egg to adult requires about 25 days under ideal conditions of 93 degrees F and 12% moisture. Both the larvae and adults produce a large amount of waste. Larval fecal pellets are pushed out of the kernel and large amounts can accumulate in the grain. The adults are winged and may fly to spread infestations.