Archaeognatha Family: Machilidae
Common name: bristletail; jumping bristletail
Adult size: 6 – 20 mm
Description: Bristletails have an elongated body, roughly cylindrical in shape. The thorax shows a definite hump and their whole body is covered in thin, tiny scales. Large compound eyes meet in the middle of the head and there are three ocelli, or little eyes…simple, light detecting organs.
Their most unique feature…the one which sets them totally apart…is their mouthparts. It is unusual because their mandibles are monocondylic…they connect to the head in only one place. The mandibles of all other insects are dicondylic…they connect to the head in two places.
Usually grey or brown in colour with distinctive mottling, they have six legs, two long flexible antenna, and three long tails with the middle one being the longest. There are several small, bendable “styli” found in the middle and hindmost sections of the body which are thought to be rudimentary appendages. They also have eversible membranous vesicles…sacs which are capable of extending and turning inside out…along both sides of their body which are specifically designed to absorb water, or moisture from their environment.
There is little metamorphic change during the nymph stages, once the eggs have hatched. Archaeognaths progressively molt through six instar stages to reach adulthood and most references claim they can live anywhere from four to eight years.
Sexually, the Archaeognaths are also a little different. Males and females do not copulate to reproduce. Rather, once they reach sexual maturity…possibly taking as long as two years…the males produce a string of spermatophores (tiny packets of sperm) on a spun thread from their abdomen. The threads are somewhat haphazardly attached to the substrate in locations where a female is likely to stumble across it…although there are some species where the males will do a courtship dance to entice a female to their spermaphores. The aroused female picks up a packet of sperm and deposits it on her ovipositor. Depending on the species, the female will lay her eggs in a suitable crevice…either singly or in batches of up to thirty eggs.
Special Notes: There are approximately 350 or more species of bristletails worldwide. They are found on every continent…including the Arctic and Antarctica.
Of particular note…when molting the bristletail must first anchor themselves to the substrate. But if the fecal material they use as an anchoring cement to hold themselves in place through the molting process should fail to hold, the bristletail is not able to complete its molt and will die.
Posted on November 24, 2016