This document discusses different types of insecticides. It defines insecticides as chemicals that kill insects. It describes the general properties of insecticides and the ideal properties an insecticide should possess, such as being toxic to pests but not harmful to other species. The document then covers various ways to classify insecticides, including by their chemical composition, mode of entry into an insect's body, and mode of action. It provides examples of different types of insecticides, such as contact and stomach insecticides, and discusses how each type works. The document also examines insecticides classified by their target life stages, such as larvicides and adulticides.