Lepisma saccharina, commonly known as a silverfish or fishmoth, is a small, wingless insect in
the order Thysanura. Its common name derives from the animal's silvery light grey and blue
colour, combined with the fish-like appearance of its movements, while the scientific name
indicates the silverfish's diet of carbohydrates such as sugar or starches.
Description Silverfish are nocturnal insects typically
13–30 mm long. Their abdomens taper at the end, giving them a fish-like appearance.
The newly hatched are whitish, but develop a greyish hue and metallic shine as they get
older. They have three long cerci at the tips of their abdomens, one off the end of their
body, one facing left, and one facing right. They also have two small compound eyes, despite
other members of Thysanura being completely eyeless, such as the family Nicoletiidae.
Like other species in Apterygota, silverfish are completely wingless. They have long antennae,
and move in a wiggling motion that resembles the movement of a fish. This, coupled with
their appearance, influences their common name. Silverfish typically live for two to
eight years. Distribution
Silverfish are a cosmopolitan species, found in Africa, the Americas, Asia, Australia,
Europe, and other parts of the Pacific. They inhabit moist areas, requiring a relative
humidity between 75% and 95%. In urban areas, they can be found in attics, basements, bathtubs,
sinks, and showers. Reproduction and life cycle
The reproduction of silverfish is preceded by a ritual involving three phases, which
may last over half an hour. In the first phase, the male and female stand face to face, their
trembling antennae touching, then repeatedly back off and return to this position. In the
second phase the male runs away and the female chases him. In the third phase the male and
female stand side by side and head-to-tail, with the male vibrating his tail against the
female. Finally the male lays a spermatophore, a sperm capsule covered in gossamer, which
the female takes into her body via her ovipositor to fertilise the eggs.
The female lays groups of fewer than 60 eggs at once, deposited in small crevices. The
eggs are oval-shaped, whitish, about 0.8 millimetres long, and take between two weeks and two months
to hatch. A silverfish usually lays fewer than 100 eggs in her lifetime.
When the nymphs hatch, they are whitish in colour, and look like smaller adults. As they
moult, young silverfish develop a greyish appearance and a metallic shine, eventually
becoming adults after three months to three years. They may go through 17 to 66 moults
in their lifetime, sometimes 30 in a single year, which is much more than usual for an
insect. Silverfish are among the few types of insect that continue to moult after reaching
adulthood. Ecology
Silverfish consume matter that contains polysaccharides, such as starches and dextrin in adhesives.
These include book bindings, carpet, clothing, coffee, dandruff, glue, hair, some paints,
paper, photos, plaster, and sugar. Silverfish can also cause damage to tapestries. Other
substances they may eat include cotton, dead insects, linen, silk, or even its own exuvia.
During famine, a silverfish may even attack leatherware and synthetic fabrics. Silverfish
can live for a year or more without eating. Silverfish are considered household pests,
due to their consumption and destruction of property. However, although they are responsible
for the contamination of food and other types of damage, they do not transmit disease.
Earwigs, house centipedes, and spiders are known to be predators of silverfish.
Etymology The scientific name for the species is Lepisma
saccharina, due to its tendency to eat starchy foods high in carbohydrates and protein, such
as dextrin. However, the insect's more common name comes from the insect's distinctive metallic
appearance and fish-like shape. While the scientific name can be traced back to 1758,
the common name has been in use since at least 1855.
Evolution Together with jumping bristletails, the predecessors
of silverfish are considered the earliest, most primitive insects and one of the first
animals to colonise dry land. They evolved at the latest in mid-Devonian and possibly
as early as late Silurian more than 400 million years ago. Some fossilized arthropod trackways
from the Paleozoic Era, known as Stiaria intermedia and often attributed to jumping bristletails,
may have been produced by silverfish. Similar species
Other similar insect species are known as silverfish. Two other silverfish are common
in North America, Ctenolepisma longicaudata and Ctenolepisma quadriseriata. Ctenolepisma
urbana is known as the urban silverfish. The Australian species most commonly referred
to as silverfish is a different lepismatid, Acrotelsella devriesiana. The firebrat is
like a silverfish but smaller and with darker markings of brown and black.
References
External links Fact sheet on silverfish highlighting habits,
habitat and threats Klass, Carolyn. "Silverfish and Firebrats".
Cornell University. Retrieved 2008-12-25. At Cornell Cooperative Extension, Insect Diagnostics
Laboratory