Insects are the most abundant and diverse form of life found on earth. Over threequarters-of a million species are known to exist, more than the number of all kinds of animals and plants put together. Insects are a vital part of the world’s ecosystem. Insects are a major link in the world food chain. Insects like bees, wasps, flies, bugs, and beetles pollinate crops. Insects destroy various weeds in the same manner that they can injure crops. Insects improve the physical conditions of the soil, and promote its fertility by decomposing plant residues and aerating the soil. Insects help control insect pests as predators and parasites. Only a few of the thousands of species are pests of mankind or his crops.