Insects inflict an enormous amount of damage upon man and his possessions, domestic animals and crops. Virtually all human communities are affected by insects in several important ways, the most obvious of which stems from their role as vectors or reservoirs of disease, whether of man, animals and plants. Although the harm done by insects as merely annoying pests is hardly comparable with the loss they cause as vectors of disease, it is by no means negligible. Insects consume and destroy large quantities of food stuffs.
In the USA, about 500 species of insects are of primary economic importance and losses caused by them range from US$ 4,000 million to $8,000 million annually.