Archaeognatha


    The common name of insects of the order Archaeognatha is bristletail, and the name of the order derives from the Greek ‘archeo' meaning ancient and ‘gnathos' meaning jaw, and refers to the primitive monocondylic way in which the mandibles connect with the head capsule (other insects are dicondylic, i.e., they have two condyles). There are about 350 known species, in 2 families, Machilidae and Meinertellidae. Bristletails are small insects, less than 20 mm in length, which possess 3 long slender cerci with the middle one much larger than the 2 outside ones. They can jump distances up to 10 cm by flexing their abdomens when disturbed. These insects lack metamorphosis; eggs hatch into young which are similar to the adults in appearance. They reach adulthood after at least eight instars, and molting continues in the adult stage. Bristletails do not copulate; males leave a spermatophore on the ground to be picked up by a female. Some species have elaborate courtship rituals to insure that females are able to locate the spermatophore. They may be found under the bark of trees, in soil or leaf litter or in rock crevices, and they are most active at night, feeding as herbivores or scavengers on algae, mosses, lichens, or decaying organic matter. Bristletails have no economic importance apart from the usual roles played by litter re-cycling organisms in ecosystems.