The general practice for many years past among naturalists has been to restrict the terms "Insecta" and "insect" to the class of Arthropods with three pairs of legs in the adult condition: bees, flies, moths, bugs, grasshoppers, springtails are "insects," but not spiders, centipedes nor crabs, far less earthworms, and still less slugs, starfishes or coral polyps.
Mosquitoes, termites, bees, ants, centipedes, millipedes, locusts, grasshoppers, butterflies, dragonflies, sandflies and spiders' are found in immense numbers.
White and red ants are very prevalent, as are mosquitos, centipedes, spiders and beetles.
Aristotle had included in one class "Entoma" the six-legged arthropods which form the modern zoological class of the Hexapoda or Insecta, besides the Arachnida, the centipedes and the millipedes.
It appears from observation of the embryo that whilst the first prosthomere of Centipedes has its appendages reduced and represented only by eye-patches (as in Arachnida, Crustacea and Hexapoda), the second has a rudimentary antenna, which disappears, whilst the third carries the permanent antennae, which accordingly correspond to the second antennae of Crustacea, and are absent in Hexapoda.