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Silverfish and Firebrats

Look-alike household pests, silverfish and firebrats can at times be difficult to tell apart.  There are subtle differences in appearance as well as the habitats in which they tend towards. Silverfish are a shiny, silver or pearl gray in color and ½ to ¾ of an inch in length.  They tend towards warm humid areas such as laundry rooms with temperatures ranging from 71-90 degrees and humidity above 75%.  Firebrats on the other hand are ½ inch in length and gray to brown in color.  They handle temperature extremes ranging from freezing to above 100 degrees and humidity as low as 30%.  Firebrats as their name implies, are common around areas of heat including ovens, heating elements, water heaters and fireplaces.  Aside from those characteristics, both species are fairly similar.  They are thin, wingless and soft-bodied with 2 long antennae.  Each has 3 long, thin, tail-like appendages.  Adults have scales that stick to many surfaces and are dust-like in appearance.

Silverfish and firebrats are nocturnal in nature resulting in their hiding during the day.  They tend to hide beneath objects and will flee in search of cover if the object they are hiding under is moved.  Both silverfish and firebrats feed on dry foods such as cereals, flour, pasta and pet foods, but they will also consume cellulose based items such as paper and book bindings.  When sources are low they will also feed on dead insects, household dust, and certain types of fungi.  They can live several months without a source of nutrition. Males perform mating dances before depositing a protected capsule on a moist surface for the female to pick up.  Eggs are a miniscule 1/25th of an inch in length and are laid in crevices, buried in food or dust or at times on cloth.  Clutches can vary from 1 to 200 eggs, with the average around 50.  Firebrats hatch in approximately 2 weeks, whereas silverfish are roughly three to four weeks on average.  Cold temperatures can result in delayed hatching of up to six weeks in both cases.  Newly hatched nymphs lack scales which appear nearly two weeks after their fourth molt.  Both species continue to molt throughout their lives and average 45-60 instar stages.  Firebrats have an average lifespan of around 2 years and silverfish around 3 years.  Development stages will vary in length of time depending on temperature.

Silverfish and firebrats cause damage to paper products and fabric by scraping their jaws across the surface.  Their mandibles are too weak to physically bite the surface.  Damage is typically in unconnected and irregular patterns with lopsided holes.  Infestations may be difficult to pinpoint as firebrats and silverfish may travel great distances in comparison to their size in order to seek out food sources.  Glue traps are often a useful tool in locating and monitoring infestations.  Keeping humidity levels low in moisture prone areas will aide in discouraging silverfish and firebrat activity.  Repair any leaking pipes immediately. Always keep dry food products in containers with tight lids.  Routine cleaning along with periodic deep cleaning to remove household dust and debris will also assist in reducing food sources.  Seal gaps around pipes and conduits within the home to prevent entry and travel throughout the home.  Pesticide applications are best preformed after cleaning, resolving humidity or moisture issues and removal of hiding places as applications done prior to completion will have decreased or little effectiveness.