Gray to light brown.
½"-5/8" (12-15 mm).
They are most abundant in attics, basements, wall voids, hollow decorative beams, dark closets, bookshelves, and storage rooms. They are often found in sinks, lavatories and bathtubs because they have fallen in and become trapped while seeking moisture.
Little is known about bristletail behavior. Most behavioral studies examined food preference or food suitability. Although most people think that bristletails feed on book bindings and carbohydrates, they actually prefer dried beef, beef extract, dead insects, and other items high in protein. Silverfish cannibalize dead and injured insects. They can survive for weeks without food and water, and more than 300 days if water is available. Silverfish prefer high humidity, although firebrats are more resistant to dryer environments. Silverfish desire cooler temperatures and are usually found in basements. Firebrats prefer warmer temperatures (over 90°F) and are often near furnaces, hot water pipes, attics, and roofing shingles.
Silverfish is a general feeder, consuming a large variety of materials. They especially eat foods and products that are high in protein, sugar, or starch. This includes vegetable foods, such as flour and cereal; fabrics, including cotton, linen, silk, and rayon; sizing in paper; starch in clothing; and paste or glue. They also eat wallpaper, book bindings, and paper when trying to feed on the glue or paste underneath them. Their damage is usually recognized from their irregular feeding marks and the presence of feces. Silverfish and firebrats can go for months without feeding.
Silverfish Prevention Tips
- You can also reduce silverfish by removing sources of food, especially in damp areas. You can reduce potential hiding places by removing old papers, books, boxes and other clutter. Seal cracks and crevices, including those found in baseboards, cupboards, and walls to limit harborages.
- Silverfish is associated with damp conditions. You can reduce their numbers by correcting moisture problems, e.g. drying out damp areas with a fan or dehumidifier, repairing leaky pipes, ventilating closed rooms, repairing leaking roofs, or sealing concrete walls and floors. If the problem occurs in a bathroom, make sure the ventilation fan is used during baths and showers. If you cannot move materials, provide air spaces between boxes and other objects to promote air circulation. Keep in mind that as air cools the humidity in that air increases, so using a dehumidifier or gently heating the surrounding air can have a big impact on the infestation.
- If the problem is associated with the roof, make sure that adequate ventilation is provided to avoid moisture accumulation. One particular problem that has been observed in the past was the installation of cedar shakes over a plywood / tarpaper base. Ventilation devices, such as soffit / ridge vents or roof vents must be installed to avoid moisture accumulation. Trees that overhang a roof may also add to the moisture build up and should be pruned back to promote air circulation.
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