Minute Aptera, with a semi-masticatory or suctorial mouth; the first abdominal segment furnished with a ventral tube or suctorial organ; the last abdominal segment but one with appendages for leaping.

This order has been established by Sir John Lubbock for the reception of a number of Insects generally known as "Spring-tails." Their scientific name is in allusion to the fact that they attach themselves to foreign bodies by a ventral suctorial tube, which contains a viscous fluid; whilst their popular name refers to their possessing saltatory appendages attached to the last abdominal segment but one. These appendages (fig. 180, D and F) consist of a long forked process which is generally bent along the under surface of the body, and kept there by a small catch. When released, the sudden extension of the elastic process throws the insect into the air. The body is covered either with hairs or scales, and the latter exhibit under the microscope very elaborate and beautiful markings (fig. 163, E). They are generally to be found in moist dark places in gardens, or on the surface of pools, and the commonest genera are Podura, Smynthurus, and Degeeria.