(Greek, thysanos = fringe)
Common Names: silverfish, firebrats
Silverfish are primitive, wingless insects covered with silvery scales
that rub from the insectís body very easily. The scales are the reason
for the common name "silver"-"fish". Silverfish are
small and flattened. Compound eyes are either reduced or absent. If eyes
are present they are formed of single elements. One, two or three simple
eyes (ocelli) may be present. Mandibles are present but may be covered by
a 'beard' of hairs. Three abdominal filaments are present. Two, equal
length appendages (cerci) arise from the sides of the second last
abdominal segment. A third (median caudal appendage) arises from the
middle of the last abdominal segment.
Silverfish may live for up to four years. Various species of silverfish
are adapted to human dwellings, but others use caves or live under bark.
Several species are commensals in ant or termite colonies. Firebrats are a
group which have adapted to the high temperatures around ovens and
Silverfish resemble the species of another ancient and flightless insect
Order, the Archaeognatha (bristletails). Bristletails differ in that they
have well developed compound eyes and the middle tail bristle is much
longer than the pair of side bristles. Silverfish are noctural insects
i.e. they feed and are active at night.
There is no metamorphic life cycle: egg-larva-pupa-adult. The juvenile
(nymph) emerges from the egg as a replica of the adult and develops through
moults. Eventually a final moult leaves it sexually mature.
Bushland species, feed on lichens and fungi. In commensal situations,
silverfish have been observed to "steal" nectar droplets from ants
that are transferring regurgitated nectar from one to the other. Firebrats
appear to feed on flour and similar materials. Household silverfish have been
noted as attacking almost anything that contains food value: paper surfaces,
starchy foodstuffs, silk, their own cast skins, other dead insects, cellulose
materials (cotton, plant debris), etc.
Silverfish do not appear to have any importance in either agriculture or
horticulture. Their significance seems to be limited to the nuisance effects or
damage done to household or paper materials stored undisturbed for extended
periods of time (e.g. archival books in libraries and museums). In bushland,
silverfish undoubtedly play a role in litter re-cycling and food chains.