By Chris Williams on November 15, 2017.

Are silverfish really silver-colored? I’m seeing these insects occasionally that I think are silverfish but they’re more brown-gray than silver. Are these something else? I need them gone. L. F., New Castle, NH

You need a professional identification and inspection to answer that question. There are two different possibilities. The most likely explanation is that you are seeing silverfish that have been around a while. Like real silver, these insects “tarnish” and wear with time. Most really are silver when they have newly molted but, as with butterflies and moths, the body scales that give them the silvery iridescent color, are rubbed off with activity and age. If you were to handle a silverfish, you would see a gray dust that rubs off on your fingers. A really old or damaged silverfish may have little silver left. Also, some silverfish species are just less silver than others to begin with.


The other possibility is that you are seeing firebrats and not silverfish. The two insects are closely related, look similar, and have similar habits but firebrats are a much darker, mottled color with no real silvery sheen. Another difference between the two is that firebrats prefer humid conditions with much higher temperatures (90-106 degrees) than silverfish. Firebrats and are more likely to be found in hot attics, around ovens, in boiler rooms, or around furnaces, fireplaces, or hot water heaters.

Silverfish like humidity but their preferred temperature range is closer to 70-85 degrees. Silverfish can be found anywhere in a house, from bedrooms to bathrooms, to basements, attics, or garages. Knowing which pest you are dealing with, and where, will help in inspection and control.


Both silverfish and firebrats have a characteristic teardrop or carrot-shaped body, about ½-inch long, with long antennae and 3 long “bristles” at their rear giving them the nickname of bristletails. They are wingless and can run quickly. Silverfish have a lot in common with cockroaches, hiding in crevices during the day and foraging for food at night (see Silverfish Have Habits Similar to Cockroaches). Like cockroaches, they feed on a range of foods but prefer carbohydrates and proteins, especially starchy materials.

Silverfish are not only a nuisance, they can damage books and papers and certain fabrics and often leave yellow stains, scales, and feces on infested materials. Cardboard boxes containing papers, fabrics, and other materials are a favorite hiding place for silverfish.

Needless to say, if you have silverfish (or firebrats), you need professional intervention. Like cockroaches, if left unchecked, silverfish can build up to high numbers and a single silverfish can live and reproduce for years. Call Colonial Pest for an inspection today!

For more on silverfish and the damage they can do, see Silverfish – The Often Overlooked Household Pest.



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