Silverfish and Firebrats

Silverfish are common pests that can live in your home and can go undected because they are nocturnal.  Seeing one or two over a long period of time should not alarm you to believe that you have an infestation.  

Listed below are some of their similarities and differences and some general control measures that you as a homeowner can take if you think you have an infestation.



Silverfish and firebrats are nocturnal and hide during the day. They come out at night to seek food and water.

Both insects prefer dry food such as cereals, flour, pasta, and pet food; paper with glue or paste; sizing in paper including wallpaper; book bindings; and starch in clothing.

Household dust and debris, dead insects, and certain fungi also are important sources of food.

They can live for several months without nourishment.

The females lay the eggs in crevices, on cloth, or buried in food or dust.

Unlike other insects, firebrats and silverfish molt continuously throughout their life, passing through 45 to 60 instars or development stages.

In apartments and homes, these insecs crawls along pipelines and through openings in walls or floors from one level to another. Sometimes you’ll see these pests in your bathtub or sink.

Even though they can’t crawl up through the drain, if they fall in they can’t climb up the slippery sides to escape.

Firebrats and silverfish have very weak mandibles, or jaws, which causes them to scrape, instead of bite, the surface of paper.



The common silverfish, Lepisma saccharina, is shiny, silver or pearl gray, and about 1/2 inch long, although it can grow as long as 3/4 inch. — The common firebrat, Thermobia domestica is shiny, a mottled gray or brown, and about 1/2 inch long.

Firebrat eggs hatch in about 14 days and silverfish eggs in about 19 to 32 days.

Firebrats live about 2 years and silverfish about 3 years.

When the temperature is below 50°F, fire brats can take as long as 300 days and silverfish as long as 500 days to develop into adults. – When it is above 75°F, it can take firebrats as few as 40 days and silverfish as little as 60 days to develop into adults.

Silverfish live and develop in damp, warm places, preferring areas such as laundry rooms that are 71° to 90°F. – – Firebrats thrive best in very warm, dry places with a relative humidity as low as 30% and temperatures above 90°F, with the optimum being 98° to 102°F.



Since firebrats and silverfish are nocturnal, you usually won’t see them.

If you are concerned that you might have a silverfish or firebrat infestation you can use sticky traps. You also can use small, glass jars covered on the outside with masking tape. The insects climb up the tape, fall into the jars, and can’t climb back up the slick sides.

Place these traps or jars in corners and along edges where foraging is likely. Because these insects can travel long distances while looking for food, it can be difficult to pinpoint the infestation source.

Household dust and debris are important sources of food, so routine cleaning will help provide effective control.

Silverfish require a lot of moisture, so using dehumidifiers in closed spaces can help discourage these pests.


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