Silverfish Facts, Identification and Control
Scientific Order: Zygentoma
Silverfish name: Lepisma saccharina
- Size: About ¼ to ½ inches long, with a “carrot-shaped” body that’s thicker near the head and grows thinner toward the posterior.
- Color: Dark grey or silver, with metallic-looking or shining scales
Signs of Infestation
Silverfish are often found around packing materials that have remained stationary for a long time. Silverfish retreat away from light very quickly when they're encountered. Silverfish are also common around any areas where they can access moisture. You may find silverfish bodies or remains near plumbing fixtures.
Silverfish may leave behind bite marks, waste, or shed skin behind. Though they can’t inflict significant damage, they may chew through paper products, linen, adhesive, or other materials in their pursuit of sugary food materials.
Treatment and Prevention
Silverfish gravitate toward humid areas. Sealing drafts, patching plumbing leaks, ensuring proper drainage and ventilation, and investing in a dehumidifier will help reduce indoor humidity and make your building less attractive to silverfish. Patch cracks around the doors, windows, ceiling, and foundation to deprive silverfish of hiding places, and possible access points.
Silverfish dislike direct light and need to live in enclosed, dark areas. Deprive silverfish of potential hiding places by storing packages, boxes, other storage material off the ground. Let natural light into rooms whenever possible, and keep naturally dark rooms like basements or attics clean. Store paper products in elevated, inaccessible locations whenever possible.
Behavior and Diet
Silverfish feed on carbohydrates like sugars and starches. They infest vegetables, flour, cereal, dried foods, dead insects, beef, and other sugary foods. If they can't access carb-rich food, silverfish can also subsist on the starches found in fabrics, paper, glue and other adhesives, bookbinding, photographs, and more.
SIlverfish prefer dark, moist, and cool locations. They’re commonly found near bathtubs, sinks, closets, basements and other humid locations. The ideal temperature for silverfish is between 70 and 80 degrees Fahrenheit, with a relative humidity between 75 and 95 percent. Silverfish avoid contact with direct light at all times.
Reproduction and Life Cycle
The speed of silverfish life cycle is mostly determined by the temperature of the rearing environment. Silverfish produce several fertilized eggs after mating. A single female silverfish can produce around 100 eggs in her lifetime. In warm environments, these eggs may hatch in as few as 19 days.
Silverfish grow slowly and must shed their skin or "molt" several times. Immature silverfish look similar to their adult counterparts, except they're smaller and don't possess scales. Silverfish can live three years or longer in humid and predator-free environments.
- Silverfish are also sometimes called “bristletails”, because of three tail-like appendages on the rear of their abdomens. The two “bristles” that point sideways are called “cerci”, while the one that points straight backward is called a “filament."
- Silverfishes’ bodies are covered in small, silvery scales. These scales detach from the silverfishes’ body very easily, which makes silverfish surprisingly difficult for predators to grab onto. These scales give silverfish their distinctive metallic or shiny appearance.
- In addition to their abdominal cerci and filament, silverfish have two long, slender antennae or “feelers." Silverfish use highly-developed sense receptors in these antennae as their primary means of navigating environments.
- Cornell University Dept. of Entomology Insect Diagnostic Laboratory “Silverfish and Firebrats” fact sheet
- University of Minnesota Extension’s Silverfish and firebrats in homes page
- Penn State College of Agricultural Sciences Department of Entomology’s Bristletails (Silverfish and Firebrats) page