They are most abundant in attics, basements, wall voids, hollow decorative beams, dark closets, bookshelves, and storage rooms. They are often found in sinks, lavatories and bathtubs because they have fallen in and become trapped while seeking moisture.

Little is known about bristletail behavior. Most behavioral studies examined food preference or food suitability. Although most people think that bristletails feed on book bindings and carbohydrates, they actually prefer dried beef, beef extract, dead insects, and other items high in protein. Silverfish cannibalize dead and injured insects. They can survive for weeks without food and water, and more than 300 days if water is available. Silverfish prefer high humidity, although firebrats are more resistant to dryer environments. Silverfish desire cooler temperatures and are usually found in basements. Firebrats prefer warmer temperatures (over 90°F) and are often near furnaces, hot water pipes, attics, and roofing shingles.

Silverfish is a general feeder, consuming a large variety of materials. They especially eat foods and products that are high in protein, sugar, or starch. This includes vegetable foods, such as flour and cereal; fabrics, including cotton, linen, silk, and rayon; sizing in paper; starch in clothing; and paste or glue. They also eat wallpaper, book bindings, and paper when trying to feed on the glue or paste underneath them. Their damage is usually recognized from their irregular feeding marks and the presence of feces. Silverfish and firebrats can go for months without feeding.

Silverfish and firebrats are primarily nuisance insects, usually causing little damage. Although very uncommon, the potential exists for large,uncontrolled infestations of silverfish and firebrats to damage paper, book bindings, wallpaper, cereals, starched fabrics, leather, fur, silk and rayon.Silverfish and firebrats are not associated with the spread of any disease.