Insect Populations in Wheat, Corn, and Oats Stored on the Farm

One or more live, stored-product insect species were found in 25.1% of the wheat, 56.4% of the oats, and 79.7% of the corn samples obtained from over 8,000 farm storages across 27 states. The average number of insects per 1,000 g in the infested samples was 26 for com, 39 for oats, and 105 for wheat. Insects of the genus Cryptolestes were the predominant pests in wheat and com, and Oryzaephilus surinamenis (L.) was the principal insect in oats. Rhyzopertha dominica (F.) was found throughout much of the grain-producing areas, including the northern states, but Sitotroga cerealella (Olivier) was only rarely detected in farm-stored grain. Plodia interpunctella (Hubner) occurred in 27.6% of the com, but was only an infrequent pest in wheat and was not detected in oats. Insect species that prefer high moisture or feed on molds were found in 28.8% of the corn samples. The incidence of insects generally increased with increased grain moisture, and average test weights per bushel were lower in infested grain than in uninfested grain. The incidence of insects and the composition of insect populations within each commodity did not vary significantly with the length of time the grain had been in storage.