Silverfish Insects: Common but Seldom Seen
One of least seen insects that can reside in your home is a crepuscular insect called the "Silverfish." Coming out at night, these tiny six-legged cigar-shaped insects typically hide in warm, humid places in the home such as in the bathroom, basements around water pipes, and any source of mild to moderate condensation.
Silverfish are active mostly at night and shun the light so unless you catch a glimpse of one upon entering a room and quickly turning on a light, you may not ever see them. You may also happen to capture one that has become trapped by the slippery enameled walls of the bath tub.
Silverfish are often found under the kitchen cabinet sinks, near windowsills and doorways, where water pipes come through walls, and around bookcases and behind walls. Near food, humidity, and cover is where they prefer to be.
Silverfish Have an Appetite for Paper Books, Textiles
Conservators of books often cite silverfish as a common vector of damage to glossy paper and book bindings. Silverfish consume the starches and adhesive gums used to produce paper and to bind books. Silverfish also eat cereal grains and sweepings that evade vacuuming and will also eat dry meat that they may find on the floor and under appliances, in cracks and floor recesses. Once silverfish have found a reliable food source they seldom travel far away from it.
Wallpaper and textiles such as clothing and some curtain fabrics (cotton, silk, rayon and linens, etc.) are also a food source for silverfish, consumed for the natural cellulose they contain. Antique textiles in storage (blankets, tablecloths, starched dollies, etc.) can also become a prime target of silverfish activity and as such, should be inspected once or twice annually for signs of infestation of both the material and the box they are stored in.
Silverfish and Wallpaper
Old wallpaper that has been infested by silverfish will show many minute pinholes of silverfish activity. The adhesive used to affix wallpaper often being a glue of flour and water provides a perfect source of consumables for these small insects where they often bore-through the paper itself causing it to have a brittle, lace-like appearance.
Cardboard boxes that have been stored in a dark basement might also show evidence of silverfish activity will have many irregular pinholes like lace if it either harbors silverfish or has served as a food source for them.
Bringing any old cardboard box used for long-term storage into the home from abroad (e.g., -from a yard sale, storage shed or garage, etc.) can be the primary vector of silverfish getting into your home. Although silverfish can survive several months without eating, if conditions for their survival exist they will continue to reside in your home.
Discovering silverfish in the home indicates both the presence of a reliable food source and possibly of an elevated humidity/moisture that they prefer. Removing one or both of these conditions, along with regular cleaning and some simple pest eradication efforts can lead to their extermination.
Although often not practical (or safe) it is suggested that if the controlled ambient temperature of a room (basement, etc.) can be raised to 440 C (approx. 1110 F) for a non-specified period of time, the heat will eradicate silverfish through desiccation. A similar treatment is being examined for in~situ bedbug eradication in the home. This procedure is likely intended for use on appliances where foodstuff accumulate; toasters, ovens, large kitchen appliances such as refrigerators that may harbor silverfish in the underside where the compressor motor and cooling fan are located. This still experimental extermination process presents many home-safety difficulties considering upholstered furniture, mattresses, and other flammables and must be left to licensed professionals.
Prevent Silverfish Pests in the Home
Plug-up any holes in walls (where cable/phone wires have been routed) to prevent entry or passage between rooms/apartments. This includes nail holes where a framed picture may have hung.
Other preventative measures against silverfish insect habitation include:
- Repair leaky faucets/pipes in and around sinks and toilets to prevent/reduce condensation
- Monitor cardboard boxes brought into the home for evidence of silverfish/other insect activity
- Vacuum floors often, especially around radiator pipes and cracks in floor, near walls, etc. where silverfish can hide
- Sprinkle diatomaceous earth, or boric acid (both are harmless desiccant materials) around crevices, corners where silverfish are spotted to cause them to dry-out
Are Silverfish Actually Harmful?
Silver generally are not harmful despite the small amount of permanent damage they can inflict upon any cellulose materials, clothing and other textiles. Silverfish are unique pests in that their presence can serve not only as an indicator of food sources for them (cleanliness of your home,) but also alert us to the presence of high humidity and conditions of condensation that favor other damage to your home such as water damage.
Leaky pipes or drains, or excessive condensation from water pipes and tanks can over the long term cause property damage to floors and walls. The presence of silverfish can be an early alert for you to inspect the home for potential water damage sources, and alert you to also search for points of entry that may allow other opportunistic and more damaging insects to invade your home.