Monday, 23 July 2012


Insects (from Latin insectum, a calque of Greek ἔντομον ", cut into sections") are a class of creatures that live in arthropods with a chitinous exoskeleton , a body of three parts ( head , chest and abdominal ) , three pairs of joints legs , compound eyes and two antennae . They are among the most diverse groups of animals on the planet, and include more than one million described species and represent more than half of all known living organisms. The number of existing species is estimated between six and ten million and potentially represent over 90% of the different metazoan life forms on Earth. The insects can be found in almost all environments , although only small number of species found in the oceans, a habitat dominated by another group of arthropods, the crustaceans .

The life cycles of insects vary, but most emerging from the eggs . Insect growth is limited by the elasticity exoskeleton and development involves a series of silent . The immature stages may differ from adults in the structure, habit and habitat and may include a passive pupa stage groups experienced a complete metamorphosis . Insects that undergo incomplete metamorphosis lack a pupal stage and adults are developed through a series of nymph stages. The high-level relationship of Hexapoda is clear. Enormity of fossilized insects have been found from the Paleozoic Era , including giant dragonflies with a wingspan of 55 to 70 cm (22-28 inches). The most diverse groups of insects appear to have coevolved with flowers plants .

Insects often move to walk, fly or swim from time to time. Because it allows a fast but steady movement, many insects tripedal take a step in walking with your legs touch the floor in alternating triangles. Insects are the only invertebrates that have evolved flight.

Many insects spend at least part of its underwater life with larvae of the adaptations that include gills and some adult insects are aquatic and have adaptations for swimming. Some species, like the shoemakers of water , are capable of walking on the water surface. The insects are mostly solitary, but some insects, like some bees , ants and termites are social and live in large colonies well organized. Some insects such as earwigs , show maternal care, guarding their eggs and young. Insects can communicate with each other in a variety of ways. Female moths can sense the pheromones of female moths over distances of many kilometers. Communicate with the sounds of other species of crickets stridulate , or rubbing their wings to attract mates and repel other males. Lampyridae beetle order Coleoptera in contact with light.

Humans regard to certain insects as pests and try to control them with insecticides and a host of other techniques. Some insects damage crops feed on sap, leaves and fruit , a bite of some humans and animals, living and dead, who feed on the blood and some are capable of transmitting diseases to humans, pets and livestock. Many other insects are considered ecologically beneficial and some provide a direct economic benefit. silkworms and bees have been used extensively by humans for the production of silk and honey , respectively.