INSECT ( Lat. insect um, insect, from insecarr, to cut in, from in, in is secure, to cut ). In its strict sense, a member of a group of six-legged arthropods known as the class Inseeta Or 1 I exa poda. Vulgarly, the tern: is applied to almost any small crawling creature: and even among naturalists until eomparatiyely recent years it was applied to the spiders and their relatives (Arachni(Ia) and to the centipedes and thousand legs (tlyriapoda). Insects constitute by far the largest group of living creatures, and in fact form much the larger part of the land animals of the world. In number of species they are more numerous than all of the other gnmps of land animals together, while in number of individuate they are countless. The most conservative esti mate places the number of species of insects in existence at tive millions, while the estimate of Riley, the famous entomologist, was ten millions. They are extremely variable in their habits.
Foot). The great majority feed upon vegeta tion of one kind or another. and practically every
part of every living plant is liable to insect attack. They feed not upon living vegeta tion, but also upon dead plant tissue in every stage of decay, and even soil mold wherever it oveurs, and are largely instrumental in the rapid disappearance of dead vegetation. Thou sands of species also prey upon animals of differ ent groups, from the warm-blooded vertebrates down to creatures of their own class and the other lower forms of animal life, They feed not only upon living animals. as parasites and predatory but also upon dead animal matter of all kinds, including excrementitious substances, as well as upon fabrics and other things eompose41 of animal material. predominating so enormously on land, insects lose their prepon derance in water, yet very many species are aquatic during the whole or some portion of their