Identification and Life Cycle
The Silverfish (Lepisma saccharina), and the Firebrat (Thermobia domestica), are closely related and both are common household pests. They can cause damage by eating foods and other materials that are high in protein, sugar, or starch.
The Silverfish are wingless insects. They are silver to brown in color with shiny silver or pearl gray fine scales covering its body. Adults are approximately 3/4 – inch in length (elongated and oval in shape), have three long tail projections and two antennae. They get their name because of their silvery light grey color and fish-like appearance. They can live and breed indoors in damp, cool locations such as basements.
The Firebrat are also wingless insects and are similar in size and appearance to the silverfish. They have three, tail-like projections protruding from their abdominal segment, two antennae (longer than their body), and are a mottled gray or tan in color with brown scales. They live and breed indoors in hot, dark areas such as around furnaces.
Silverfish and firebrats are able to live without food for several months. The develop slowly under normal household conditions and have a life span of 2 to 8 years. They lay eggs during any time of year in secluded areas such as behind books or on dark closet shelves. The female silverfish typically lays a few eggs at one time, and only about 50 eggs in her lifetime. They are oval shaped, whitish eggs that can take 19 to 43 days to hatch. Firebrats deposit approximately 50 eggs at one time, and hatch in 14 days or longer depending on its environment. Both reach maturity in 3 to 24 months.
Habits and Damage
The silverfish and firebrat are nocturnal, and hide during the day and feed at night. These insects and their eggs can unknowingly be brought into your home in cardboard boxes, old books, old starched clothing, newspapers, and other carbohydrate materials.
They will eat any of the foods humans eat, and primarily feed on starch, protein or sugar. They do not carry disease, but can cause damage by feeding on cereals, moist flour, any paper where there is glue applied, such as wall paper and book bindings. They will also damage clothing and drapery; starched cotton, linen, and silk. They seldom damage wool fibers, fur or other animal-based materials.
Silverfish can be found hiding in dark, damp places including basements, laundry rooms, attics, kitchens, and behind baseboards, under and around sinks, window and doorframes, and inside walls of new homes where the plaster is still damp.
Firebrats can be found in hot, dark places including attics, around furnaces and fireplaces, stove and oven areas, hot water heaters, and in insulation around hot water and hot pipes. They can follow pipelines from the basement to the rooms on lower floors where they find food.
Common Signs Of Silverfish & Firebrat Activity
- Oddly Shaped Holes. They feed on and can damage books, newspapers, cardboard boxes & clothing. These holes are sometimes accompanied by yellow stains.
- Discarded Exoskeletons. Often the first noticeable sign of an infestation you will see is when they molt, or shed their exoskeleton.
- Scrapings or Holes in Wallpaper. They feed on the paste behind the wallpaper causing damage.
- Visual Sighting. You may find these insects hiding in or near damp areas of your home such as in your shower or bath eating items that contain cellulose such as shampoo or shaving cream.
Prevention and Management
The best strategy for silverfish and firebrat control is prevention. An Integrated Pest Management (IPM) program can properly identify the insect and help you maintain a pest-free environment.
It is important to recognize and alter conditions in and around a home to limit areas where silverfish and firebrats can gain access from the outside, and find safe harborage and food inside.
Exclusion. Limit areas where they can gain access into structures, especially around doors & pipes.
Sanitation. Reduce the possibility of an infestation by eliminating possible living and breeding conditions.
Modify Habitat. Change the environment around the dwelling by reducing the number of harborage areas.
The following steps can be taken to help prevent or reduce a potential problem with silverfish & firebrats.
- Provide suitable drainage for basements, cellars, and crawl spaces under the building to reduce moisture.
- Dry out damp areas by using a dehumidifier.
- Fill all visible cracks and voids in the foundation as well as around windows, doors & screens.
- Seal all cracks & crevices around plumbing pipes, electrical and gas lines, and in cupboards.
- Install door sweepers to insure that doors close tightly.
- Regularly vacuum carpets and immediately clean up spilled drinks and food.
- Store sugar and starch based foods such as breads and cereals in airtight containers.
- Repair leaking faucets, water pipes, and air conditioning units to reduce moist soil conditions.
- Inspect books, newspapers & other cellulose items for signs of damage. If possible, seal in plastic containers.