Three-pronged bristletails (Order: Thysanura)

A photograph of a Silverfish (_Lepisma saccharina_).

Silverfish (Lepisma saccharina) are commonly found inside houses.

The term thysanura is derived from the Greek thysanos meaning fringed and ura meaning tail. Three-pronged bristletails can be up to 2cm long, with a carrot-shaped body and a long tail consisting of 3 fringed filaments, two of which are cerci and one of which is called the epiproct.

These insects mostly live in leaf litter and crevices in wood. However, they include the familiar Silverfish (Lepisma saccharina) which has scales on its body and likes human dwellings, especially slightly moist areas, where they eat starchy food such as paper. If you put the light on in a dark room at night - especially the kitchen or bathroom - you might see them scurrying quickly away.

The Firebrat (Thermobia domestica) is also a three pronged bristletail which is bristly rather than scaly, and again likes human dwellings, especially warm places such as hearths, heating ducts and bakeries.

Although they are tiny and primitive, the bristletails have a mating ritual that involves the male dancing around near a female and leaving a spermatophore on a silk thread. The female then picks this up between the valves of her ovipositor.

The eggs are laid in cracks and crevices. When the young hatch from the egg they are like miniature adults, but without the scales. They moult ten times, and unlike the more developed winged insects they moult all their adult lives.

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