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. |