Silverfish and Firebrats Pest Note

Information on silverfish and firebrats can also be seen on the Healthy Canadians website.

Silverfish and Firebrats - What are they?

These wingless, flat insects have two long slender antennas on their head and three long slender "bristles" at the rear of their tapered carrot-shaped body. They are 1/2 inch long when fully grown. Sometimes these insects are referred to as "bristletails". The young resemble the adults except they are smaller, and the eggs are whitish, oval, and about 1/32 inch long.

Silverfish are covered with shiny silver scales that give the body a metallic sheen. Silverfish and firebrats are nocturnal insects that are commonly found in attics, basements, bathrooms, wall voids, subfloor areas and cracks or crevices. These insects normally hitchhike into the home in food, furniture, old books, papers and old starched clothing. They may be found almost anywhere in the house, but are most commonly found in damp, cool locations (preferring 75 to 95% relative humidity) such as around sinks, bathtubs and other plumbing fixtures where they fall in seeking moisture and are unable to climb out. Sometimes they are attracted to new buildings where the walls are still damp from plaster and green lumber.

Silverfish are most active at night and move very quickly with a wiggling motion that resembles the swimming action of a fish.

Firebrats are similar to silverfish in overall appearance, but lack the silvery sheen. The body is gray or brown with bands of dark scales, usually with numerous dark markings that give a mottled appearance. Unlike the silverfish that may be found in any part of a house, firebrats prefer warm high temperatures and humidity. Firebrats are more common in attics and around furnaces, ovens and water heaters.

These insects follow pipelines from the basement to rooms on lower floors and live in bookcases, around closet shelves, behind baseboards and behind window or door frames. They are hardy and can live without food for many months.

What can they do?

Silverfish and firebrats are harmless to humans but are undesirable due to their appearance.

They are scavengers and will feed on crumbs, dead insects, starch, glue, wallpaper paste and paper products. They can also stain fabric, paper, books or wallpaper. Damage to these items can be significant if very large infestations have been present over a long period of time.

Populations are slow to grow, and a large house infestation usually indicates a long-time infestation.

How can I manage them?

Sanitation to control silverfish and firebrats

Sanitation is the first and foremost element of any effective silverfish and firebrat control program and is most suitable for the control of all crawling insects.

• Vacuum regularly to help remove food particles and insect egg masses.
• Regularly clean around and behind appliances and machinery, inside cupboards, drawers and pantries and keep countertops clean. Also clean beneath sinks and other dark or humid locations.
• Wrap or insulate pipes that have excessive condensation, repair leaky faucets and pipes, ventilate bathrooms and dehumidify areas of excess moisture.

Traps

Silverfish and firebrats can be easily trapped in small glass containers (e.g., baby food jars). Wrap the outside of the glass with tape and set the container upright in areas where you have seen silverfish or firebrats. The insects will climb up the taped surface, but they will be trapped in the glass container because they cannot climb smooth surfaces.

Products

The majority of domestic pesticides available to homeowners for controlling silverfish and firebrats contain propoxur. These products can be purchased at garden centres or hardware stores. By following the directions for application on the label, these products can be effective in reducing the number of silverfish and firebrats infesting a household. However, these chemicals may not take effect immediately because silverfish and firebrats hiding in wall voids must come out and come into contact with the insecticide. Results can be expected within 10 to 14 days.

Diatomaceous earth, an active ingredient found in other pesticides, is composed of crushed microscopic marine organisms and is an ecological means of control. This powdery dust is much like an abrasive, it removes the waxy coating on the insect's skin that normally prevents the insect from losing water. After coming into contact with the dust, the insect dies from dehydration. Diatomaceous earth can be applied along baseboards and beneath and behind appliances to control crawling insects, and is non-toxic to humans (avoid breathing the dust).

Boric acid dust can also be used for firebrats and silverfish. Boric acid has the advantages of being very low in toxicity and very long lasting if applied in dry voids where it will remain undisturbed.