Insect pests are serious plant destroyers. They attack the parts and products of plants at all the stages of their life.

Insects can attack the plant in three ways-that is, by chewing the crop plants, by sucking the cell sap from various parts of plants, and by damaging the crop internally.

Methods to control insect pests are as follows:

(i) Mixing insecticides with the soil helps in controlling root-cutting-type insects. In this method, the insecticides are mixed in the soil of the field before sowing the crops, for example, chloropyriphos.

(ii) Dusting or spraying the insecticides helps in getting rid of stem- and leaf-cutting insects. Here, the insecticides are sprayed on the stems and leaves of the plants, for example, malathion.

(iii) Spraying systemic insecticides (insecticides that enters the plant tissues via roots or shoots) helps in controlling sap-sucking insects. A systemic insecticide penetrates the tissues of the host plant without causing any harm to the plant. Insects feed on the insecticide and die, for example, dimethoate and metasystox.