Entomology is a major branch of zoology concerned with the study of insects. Specialists in this science are called entomologists; They study animals related to this science, such as ticks, weevils, spiders and centipedes (the mother of forty-four), and these types are arthropod animals. See: the arthropod animal. Entomology developed rapidly after the 1850s when Swedish botanist Carolus Linnaeus created a useful system for classifying and naming plants and animals. Entomologists research the anatomy, physiology, evolution, life history, behavior, structure, and taxonomy of insects and arthropods. There are a million and a half known species of insects, but the estimated number is ten million. Insects are a major competitor to humans in food and textiles; Insects such as grasshoppers and locusts alone cause spoilage in many agricultural crops each year. Most entomologists work in the field of economic entomology, also called applied entomology; They study insect pests that spoil crops and ornamental trees, stored products and buildings, or spoil everything related to human and animal health. Agricultural entomologists study food and textile insect pests. Forest entomologists study wood pests. Medical entomologists and veterinary entomologists seek to reduce the risk of insects that cause disease to humans and animals, as scientists have reduced the number of insect pests through various controls, including agricultural controls such as draining swamps that breed mosquitoes and some flies, and chemical controls such as the use of insecticides and repellants. , and biological controls such as the use of animals that feed on insect pests. Many insects are considered beneficial to humans: for example, the silk worm gives valuable threads, as well as bees, which not only give us honey and wax, but also pollinate many types of plants. Some insects, such as mantis, ladybird, and other insects feed on insect pests. Entomologists are also seeking to protect these auxiliary species and increase their numbers.