Spring-tails

Spring-tails (Collembola), an order of primitive wingless insects which, along with the somewhat similar Thysanura, are included in the small group Apterygota. The popular name refers to a peculiar springing fork which is usually present on the abdomen. It seems to result from a pair of abdominal appendages which are united at the base and bent forward when the animal is at rest. 'By a process analogous to that by which the common toy frogs are made to jump,' the spring-tails leap to a considerable height. The Collembola are all small, usually under a quarter of an inch in length; there are six or fewer abdominal segments; there are no compound eyes, nor hints of wings, nor metamorphosis. They usually live in damp and sheltered places—e.g. under bark or stones. Among the representative forms may be noted Podura aquatica, common on stagnant water in England; Orchesella cincta, among dead leaves and moss; Desoria glacialis, on the glaciers; Smynthurus; Isotoma; Macroto. See Sir John Lubbock, Monograph of the Collembola and Thysanura (Ray Society, 1873).