Insects damage stored grain in two ways:
1. Direct feeding damage, resulting in loss of weight, loss of nutrients, reduction in germination, reduction in grade and a lowering of market value.
2. Deterioration and contamination by their presence, resulting in downgrading of grain and lowering of market value because of foreign matter in grain (insects and insect parts), odors, molds and heat-damaged grain.
"PB1395-Insects in Farm-Stored Grain: 2009 Prevention and Control," The University of Tennessee Agricultural Extension Service, PB1395 11/09(Rev) 10-0095, http://trace.tennessee.edu/utk_agexcrop/18