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Silverfish and firebrats


About 1/2 inch
Silverfish and firebrats are common indoors throughout the United States. Both are active at night and hide during the day. In apartment buildings these insects follow pipelines from the basement to the rooms on lower floors where they find food. They may be found in bookcases, around closet shelves, behind baseboards, and behind window and door frames.



Live in damp, cool places, especially basements
Large numbers can sometimes be found in new buildings if there are plaster walls that are still damp


Firebrats live in warmer, dark places such as around furnaces, fireplaces, and in insulation around hot water and heat pipes.


Both silverfish and firebrats are slender-bodied, about 1/2 inch in length and wingless. Their bodies are covered with scales, shiny silver or pearl gray for silverfish, and mottled gray for firebrats. The immature insects look like adults but are smaller in size. Both have two long antennae at the head end and three long tail-like appendages at the hind end. The appendages are almost as long as the body.


Silverfish and firebrats develop slowly under usual household conditions, and produce few young. They are able to live without food for several months. The females lay eggs at any season in secluded places, such as behind books or on closet shelves. Silverfish and firebrats may reach maturity in 3 to 24 months.

Silverfish lay eggs singly or only a few at a time, but may deposit several batches over a period of weeks.

Firebrats deposit about 50 eggs at one time, and again, may lay several batches. Eggs hatch in 2 weeks or longer, and the rate of growth of the young depends on the temperature and humidity in the building.


Silverfish and firebrats cause damage in homes by eating foods and other materials that are high in starch, protein, or sugar. They feed on cereals, moist flour, any paper on which there is glue or paste, sizing in paper including wall paper and book bindings, starch in clothing and some fabrics. They eat holes in paper and may consume the paste that holds wallpaper to walls. Ragged edges on bindings of books may be a result of the feeding. On fabric there may be feeding marks on individual fibers, and yellowish stains, expecially on linens. Firebrats are said to prefer rayon fabrics.
Further sources: Goulson, D. 2003. Bumblebees: Their Behaviour and Ecology. Oxford University Press, 240 pages.
Kearns, C.A. and J.D. Thomson. 2001. The Natural History of Bumblebees:
A Sourcebook of Investigations. University of Colorado Press, 120 pages.
Prepared by: Kathryn Gardner, Carolyn Klass, and Nicholas Calderone
Date Prepared: July 2004

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