Silverfish and their close relatives Firebrats are characterized by three long tail-like appendages arising from the tip of the abdomen.
They have chewing mouthparts, long antennae and the body is almost always covered with scales.
Silverfish have a carrot-shaped outline. They are usually a steel gray or metallic silver colour and measure about 1/2 – 3/4 inch in length. They prefer warm, damp, dark and undisturbed areas.
Silverfish may roam some distances in search of food. They consume both carbohydrates and proteins. Silverfish are pests of paper products and textiles. They are particularly fond of paper with a glaze on it. This glaze is usually a starch compound which they prefer. Silverfish will also eat the glue backing in wallpaper. These insects prefer textiles that are cotton or artificial silk. They generally will not attack woolens or true silk.
Female adults lay one to two eggs a day. They can live up to three and a half years passing through an unknown number of molts.
Silverfish and firebrats feed and cause damage to a variety of materials, but seem to prefer materials of plant origin that are high in carbohydrates and protein. They feed on glue in book bindings or behind wallpaper, and on paper, paper sizing, cereal grain products and dried meat. Silverfish may also damage silk and some synthetic fabrics, but they usually avoid woolens.
Silverfish and firebrats prefer dark places and are most active at night. Most species are found outdoors in hidden locations, such as under tree bark and rocks, or in the nests of animals, but human dwellings provide a good environment for a few species. Inside the house, bristletails can be found almost anywhere, but they are most abundant in:
- Wall voids
- Hollow decorative beams
- Dark closets
- Storage rooms
They are often found in sinks, lavatories and bathtubs because they have fallen in and become trapped while seeking moisture.
Houses with wooden shingles seem to be particularly attractive to bristletails, which can enter the home from under these shingles. In addition, infestations can start when eggs, nymphs or adults are brought into a house on infested cardboard boxes, cartons, furniture or similar items.
Silverfish and firebrats are long-lived insects. Development time from egg to adult takes anywhere from three months to three years for silverfish, whereas firebrats complete development from egg to adult in about four months. Adult silverfish and firebrats may continue to live for up to three years. This equals a potential lifespan of approximately six years for silverfish and three to four years for firebrats. Adults continue to molt throughout the remainder of their lives.
Adults lay eggs in cracks and crevices near food sources. Depending on species, adults lay 5-50 eggs per clutch. These eggs hatch into nymphs, which look like small adults. They molt several times during the nymph and adult stages and have been observed to shed their skins more than 30 times a year. Development time from egg to adult varies between the four house-dwelling species.
This pest prefers dark locations, resulting in difficulty finding their breeding locations. An experienced pest professional will usually have more success in treating silverfish than most homeowners.
Infestations usually start when infested materials are brought into the home. When possible, inspect and treat all boxes, furniture, cartons or other items that have been used or stored in infested areas. Caulking holes and cracks, which allow silverfish to enter from outside, will help prevent infestations. Reduce potential food sources by storing old books, papers, starched linens and cardboard boxes in sealed plastic containers.
Lowering the humidity and temperature in a house will also help control silverfish, since they generally prefer high humidity and moderately high temperatures. Lowering the temperature in areas around hot water pipes, water heaters and boilers will reduce firebrat populations. Improved air circulation in these areas will usually lower temperatures slightly.