Silverfish

• It belongs to one of the oldest lineages of living insects: its ancestors already looked like this before wings appeared in insects, more than three hundred million years ago.
• Unlike almost all insects, it goes on moulting throughout its adult life, and can do so fifty or sixty times and live for several years.
• Its courtship lasts hours: male and female perform a dance with their antennae until he deposits on the ground a packet of sperm that she picks up, with no direct contact.
• It belongs to one of the most ancient insect lineages: the Zygentoma have no wings and never had any, unlike fleas or lice, which lost them. Its shape has remained practically the same for more than 300 million years.
• It keeps moulting as an adult, something almost no insect does: it can moult more than fifty times over its lifetime, and live up to eight years.
• It digests cellulose by itself, with its own enzymes: it eats paper, bookbinding glue, starch from clothing and food scraps, and that is why it is a conservation problem in archives and libraries.
• Its courtship is elaborate and involves no contact: the male spins a silk thread between the floor and a wall, deposits a spermatophore beneath it and guides the female to it with a dance of antennae that can last half an hour.
• Its silvery scales come off easily and let it slip away from spiders and out of its own moults; that metallic sheen and its undulating movement are what earn it the name silverfish.
• It needs high humidity, and that is why a well-ventilated, dry house is the best control.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Damp, dark corners of houses: bathrooms, kitchens, cellars and cupboards

Size at birth

The newly hatched nymph measures a little over 1 mm and is whitish: it does not yet have the silvery scales, which appear around the third moult

Sexual maturity

An ametabolous life cycle: moulting continues after sexual maturity is reached and the adult renews its cuticle many times during its life, which is exceptional among insects

Gestation / incubation

Incubation lasts between 20 and more than 40 days depending on temperature and humidity; development from egg to adult can take from a few months to two years

Litter / clutch size

The eggs are laid one by one or in small groups, normally no more than 30 at a time, in cracks and crevices; a female can exceed 100 eggs over her lifetime

Sources consulted: Natural History Museum de Londres · Instituto del Patrimonio Cultural de España · Sturm y Machida, revisiones de Zygentoma · Richards & Davis 1977 via ficha de especie · Oklahoma State University Extension · Child 2007 y Richards & Davis 1977 via fichas de especie · Insects Limited · Richards & Davis 1977 via ficha de especie de Lepisma saccharinum · Animal Diversity Web, Lepisma saccharina · fichas de ciclo biologico de Lepisma