Small grains, including wheat, are harvested in spring and stored through the hottest and most humid months of the year. These conditions make it extremely difficult to prevent damage.
Corn also can be difficult to store because of field infestation by maize weevil.
And, soybeans are a challenge because few insecticides are registered for use in stored soybeans. Insects that attack grains and grain products are beetles, their larval stages, and the larval stages of moths. There are many different kinds of these insects. Their length varies from about 0.0625 inch to as much as 1.25 inches long. Some of the more important beetle pests are the maize weevil, rice weevil, saw-toothed grain beetle, lesser grain borer, cadelle, confused flour beetle, red flour beetle, bean weevil, drugstore beetle, cigarette beetle, flat grain beetle, dermestid beetle, and mealworm.