Insects are responsible for significant losses to the world's total crop production annually. Not all insects are pests but a small number are harmful to crops, livestock and humans. One major reason for the occurrence of these pests is the creation of man-manipulated habitats, with crops selected for their large size, high yield, nutritious value, and clustered in a confined area. This provides a highly conducive environment for herbivorous insects. Good post-harvest management and storage conditions are important in reducing losses caused by insect infestation.

Vertebrates - while field crops are usually vulnerable to vertebrate pest damage during a short portion of the growing season, stored foods are vulnerable for as long as they are held in storage. Crops are at risk of consumption, contamination and spoilage by rats, mice and birds. Contamination can lead to further disease risks. Good post-harvest management and storage conditions are most important in reducing pest losses.