How to Bug Proof Your Home: Silverfish and Firebrats

Pest Management In and Around Structures May 20, 2009 Print Friendly and PDF

Introduction

Silverfish and firebrats are sometimes known as bristletails. They often live in damp, cool places such as basements, bathrooms and laundry rooms. Adult silverfish and firebrats are up to 3/4 inch in length. They are wingless insects with two long, slender antennae, and a flat carrot-shaped body, covered with scales, that tapers down to three long “bristles” at the end. Both silverfish and firebrats move fast in a wiggling motion, resembling the swimming action of a fish.

Houses provide a perfect habitat for silverfish. Preferring moderate temperatures between 70 and 80 °F, and a relative humidity of between 75 to 95%, they collect near sinks and other plumbing fixtures in bathrooms, kitchens and basements. Silverfish are most often discovered in sinks and bathtubs, though they can be present throughout the house. Silverfish are frequently introduced with newly installed dry wall, feeding on the paper backing and occasionally large populations form within new buildings where the walls are still damp from plaster and fresh lumber.

Firebrats normally live outdoors under rocks, leaves and inside bird nests where heat and moisture are generated by the natural composting process. However, they are also known to occur in homes. Like silverfish, firebrats enjoy a humid environment, however they prefer much higher temperatures of 90°F and above. Consequently, they are discovered less, because they collect around furnaces in basements, water heaters in attics, inside fire-places and within the insulation surrounding hot water pipes.

Silverfish and firebrats are mostly nocturnal, foraging at night. They prefer vegetable matter with a high carbohydrate and protein content. Indoors however, they will feed on almost anything, including dried meat, other insects, starch, paper, glue, sugar, molds, cereals and fabric containing cotton, linen, rayon and silk. They seldom damage fibers of animal origin such as wool or hair. These insects are hardy and can live without food for up to one year.

Silverfish and firebrats are considered pests because they consume and stain foods, fabric, books and wallpaper. Damage is manifested as yellowish stains and notched edges, although this is not usually observed. Significant damage is only found in the case of a large infestation that has been present over long periods of time. Molted scales and excrement are also left behind.

Prevention

  1. Fabric and stacked paper products should not be stored for long periods.
  2. Spilled food must be cleared away.
  3. Reduce water availability by repairing leaky plumbing and installing adequate extraction fans for laundry and bathroom areas.
  4. Lowering the home’s relative humidity can be accomplished with dehumidifiers. Lighting a dark area is helpful as it forces the insects out of their shelter to new sites where they can be managed more easily.
  5. Outdoors, mulch should not be placed touching the house.
  6. In the case of a severe infestation, household formulations of boric acid may be helpful. Eradicating these insects can be difficult as they often reside between wall partitions, in insulation materials and in other protected places.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.