Insecticide is a kind of pesticide with the largest dosage and variety. Generally, most pesticides can only kill insects but not prevent diseases. Pesticides have played an extremely important role in increasing agricultural production and solving human food problems, but they are also the most important factor causing environmental pollution (such as organochlorine pesticides, which are stable in chemical properties, difficult to degrade and easy to accumulate in soil and organisms), and are also closely related to the reduction or even extinction of natural enemies of beneficial organisms such as pests.
Insecticides are mainly used to control agricultural pests and urban health pests, with a long history, large dosage and many varieties. In the 20th century, with the rapid development of agriculture, pesticides greatly increased agricultural output.