Insects are extremely numerous and widespread everywhere. Currently, about a million species of insects are known. Insect science - entomology - has elucidated the huge role insects play in human life. Some insects destroy crop crops and damage forests; others are parasites and vectors of human and domestic infectious diseases. But there are also useful insects - pollinators of cultivated plants - bees that provide valuable products - honey and wax, silkworms, as well as predators and parasites that exterminate harmful insects.