Silverfish and Firebrats
What are they?
Silverfish and firebrats are harmless to humans, but are considered pests because of their appearance.
These wingless, flat insects have two long, slender antennas on their head and three long, slender "bristles" at the back of their tapered carrot-shaped body. Sometimes these insects are called "bristletails." They are just over 1 cm (.39 inches) long when fully grown. The young look like the adults (except they are smaller), and the eggs are whitish, oval, and about .8 mm (.03 inches) long.
Silverfish are covered with shiny silver scales that give their body a metallic sheen. Firebrats mostly look like silverfish, but lack the silvery sheen. Their body is gray or brown with bands of dark scales, usually with many dark markings that give a mottled appearance.
Should I be concerned?
Silverfish and firebrats 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. There can be a lot of damage to these items if very large infestations have been present over a long period of time.
Populations are slow to grow, and a large house infestation usually means they have been there for a long time.
How do I know if I have a problem?
Silverfish and firebrats are night insects that are often found in attics, basements, bathrooms, wall voids, subfloor areas, and cracks or crevices. They normally hitchhike into the home on food, furniture, old books, papers, and old starched clothing.
Silverfish may be found almost anywhere in the house, but are most commonly found in damp, cool locations (preferring 75 to 95% relative humidity). For example, you may find them around sinks, bathtubs, and other plumbing fixtures where they go for moisture, fall in, and can't 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 looks like the swimming action of a fish.
Unlike silverfish, which 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.
Both silverfish and firebrats 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.
Silverfish and firebrats (bristletails) are from the tropics, but have been able to adapt to temperate countries by living in damp and warm locations. Bristletails and their eggs can be unknowingly moved from one area to another in cardboard cartons, books, paper, and pantry products.
How can I get rid of silverfish and firebrats?
Cleaning is the most important part of controlling silverfish and firebrats, as it is for all crawling insects.
- Vacuum often to help remove food particles and insect egg masses.
- Regularly clean around and behind appliances and machinery, inside cupboards, drawers, and pantries.
- Keep countertops clean.
- Also clean beneath sinks and other dark or humid locations.
- Wrap or insulate pipes that have too much moisture. Repair leaky faucets and pipes. Ventilate bathrooms and dehumidify areas of excess moisture.
Silverfish and firebrats can be easily trapped in small glass containers (like 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.
If you use a pesticide to control your pest problem, read the label to make sure you are choosing the right product for the right pest. Follow all label directions and warnings carefully. Always look for a Pest Control Products (PCP) number on the label so you know the product has been approved by Health Canada. See Use pesticides safely for more information on using pesticides safely
- Pesticides available to homeowners for controlling silverfish and firebrats can be bought at garden centres or hardware stores. By following the directions on the label, these products can be effective in reducing the number of silverfish and firebrats infesting your home. 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 in 10 to 14 days.
- Diatomaceous earth is made of crushed microscopic marine fossils and is an ecological means of control. This powdery dust works like an abrasive: as insects crawl over the powder, their outer "skin" is scratched, causing them to dehydrate and die. Diatomaceous earth can be applied along baseboards and beneath and behind appliances to control crawling insects. It is non-toxic to humans and pets (but 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.
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