An order of small wingless insects, the springtails, less than 10 mm long, which leap by means of a specialized forked organ (furcula) that is attached on the underside of the abdomen by a special catch (retinaculum) and acts as a spring. The mouthparts are largely concealed within folds of the head. Most springtails are scavengers but some are pests of leguminous plants. Although some authorities place the Collembola in the subclass Apterygota, with other wingless insects, others regard them as constituting a separate class within the superclass Hexapoda, most closely affiliated with the Protura.