Primary insect pests

Insects considered as primary pests of stored products cause damage to stored grains by directly feeding on the grain at some point in their lifecycle. Primary pests will attack grains that are intact and stable. Whole sound grain is stable when its temperature and moisture content are below the levels needed for germination. Primary pest species often develop and reproduce very quickly when the conditions are optimal. This allows for large populations and, therefore, considerable damage to ensue within a matter of a few months.

Many species of stored product beetles feed internally in grain kernels as larvae. Rusty grain beetles, weevils, and lesser grain borer all develop initially inside the kernel. Of the moths, only the Angoumois grain moth is an internal feeder.