the insect

                                                     

                                THE INSECT

As part of our subject we draw the different parts of the body of an insect . The study of insect is called Entomology .Insect are the most numerous animals on earth 97% of insect are benificial to man Insects (from Latin insectum, a calque of Greek ἔντομον [éntomon], "cut into sections") are aclass of invertebrates within the arthropod phylum that have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed legs, compound eyes and one pair of antennae. They are among the most diverse groups of animals on the planet, including more than a million described species and representing more than half of all known living organisms. The number of extant species is estimated at between six and ten million, and potentially represent over 90% of the differing animal life forms on Earth. Insects may be found in nearly all environments, although only a small number of species reside in the oceans, a habitat dominated by another arthropod group, crustaceans.

The life cycles of insects vary but most insects hatch from eggs. Insect growth is constrained by the inelastic exoskeleton and development involves a series of molts. The immature stages can differ from the adults in structure, habit and habitat, and can include a passivepupal stage in those groups that undergo complete metamorphosis. Insects that undergoincomplete metamorphosis lack a pupal stage and adults develop through a series ofnymphal stages. The higher level relationship of the hexapoda is unclear. Fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonflies with wingspans of 55 to 70 cm (22–28 in). The most diverse insect groups appear to havecoevolved with flowering plants.

Adult insects typically move about by walking, flying, or sometimes swimming. As it allows for rapid yet stable movement, many insects adopt a tripedal gait in which they walk with their legs touching the ground in alternating triangles. Insects are the only invertebrates to have evolved flight. Many insects spend at least part of their lives under water, with larvaladaptations that include gills, and some adult insects are aquatic and have adaptations for swimming. Some species, such as water striders, are capable of walking on the surface of water. Insects are mostly solitary, but some, such as certain bees, ants and termites, are social and live in large, well-organized colonies. Some insects, such as earwigs, show maternal care, guarding their eggs and young. Insects can communicate with each other in a variety of ways. Male moths can sense the pheromones of female moths over great distances. Other species communicate with sounds: crickets stridulate, or rub their wings together, to attract a mate and repel other males. Lampyridae in the beetle order Coleopteracommunicate with light.

Humans regard certain insects as pests, and attempt to control them using insecticides and a host of other techniques. Some insects damage crops by feeding on sap, leaves or fruits. A few parasitic species are pathogenic. Some insects perform complex ecological roles; blow-flies, for example, help consume carrion but also spread diseases. lnsect pollinators are essential to the life-cycle of many flowering plant species on which most organisms, including humans, are at least partly dependent; without them, the terrestrial portion of the biosphere (including humans) would be devastated. Many other insects are considered ecologically beneficial as predators and a few provide direct economic benefit. Silkworms and bees have been used extensively by humans for the production of silk and honey, respectively. In some cultures, the larvae or adults of certain insects are a food-source for humans.

        There are the one who transmit disease to human , animals and plants . Compete with humans and other animals for food . There are feeders on crops and ornamental plants . I’ved learned that despite of there negative effects there are important in our ecosystem . These insects are the pollination agents of most fruit and vegetables . They serve as food for fish, bird ,animals and man . They destroy dangerous insect  . They provide useful food and materials for man like wax,honey, silk and other products . They assist in the decomposition and recycling of organic matter; dead plants and animals .  Insect are balancing our ecosystem , without these insect our ecosystem will be unbalance and will lead to deterioration of our environment .

 Insect are identify by the documented evidence obtained from classification to order, Life cycle , damage cause and their habitat . They are  classify based on the standard classifiacation system ,Anthropods, three distinct body regions :the head, thorax and abdomen .