Silverfish and Fire Brats: Thysanura

Physical characteristics: Adult silverfish measure up to 0.4 inches (10.2 millimeters) in length. Their bodies are covered with silvery scales.

Geographic range: Silverfish probably originally came from tropical Asia; the species is now found living with people worldwide.

Habitat: This species lives in warm, damp places in the home, especially basements, closets, bookcases, shelves, and baseboards.

Diet: Immature and adult silverfish are fond of flour and starch and are sometimes found in cereal; they also feed on muslin, starched collars and cuffs, lace, carpets, fur, and leather. They are also cannibalistic, feeding on molted silverfish skins and dead and injured individuals.

Immature and adult silverfish are fond of flour and starch and are sometimes found in cereal; they also feed on muslin, starched collars and cuffs, lace, carpets, fur, and leather. (Mark Smith/Photo Researchers, Inc. Reproduced by permission.)

Behavior and reproduction: Silverfish forage, or search, for food at night. They spend their days hidden in dark, protected places.

The male spins a silk thread and deposits a packet of sperm underneath; the female picks it up and places it in her reproductive opening. Eggs are laid singly or in small batches of two to three and deposited in crevices (KREH-vuh-ses) or under objects. Under the best conditions, a female lays an average of one hundred eggs during her life span. The larvae have no scales up to the time of their third molt. After ten molts, they reach sexual maturity; the adults, with a life span of two to eight years, keep molting about four times every year.

Silverfish and people: Silverfish are considered household pests because their feeding activities damage household goods.

Conservation status: Silverfish are not threatened or endangered. ∎