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Silverfish
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Silverfish

The silverfish is a common insect that gets its name from its color (light grey or silver) and the fish-like wiggling movements it makes. These pests do not transmit disease, but they can do damage to your home by feeding on starch-rich materials like paper, wallpaper, and fabric as well as food.

About Silverfish

Silverfish are believed to pre-date even cockroaches, coming into existence 400 million years ago! They have a longer-than-average lifespan for an insect, living up to eight years if not killed by predators that include spiders, centipedes, and earwigs. Because they are a preferred food for these pests, the presence of silverfish can attract other nuisance bugs to your home.

What do silverfish look like?

Silverfish range from 1/4” to 1” in length. Their bodies consist of a head, abdomen, six legs, two compound eyes, two long antennae, and three appendages that resemble tails. The body of the silverfish is flat and narrow and tapers down from the head in the shape of a carrot. It is covered in shiny, silver-grey scales. Two of the tail-like appendages, called cerci, point to the sides of the body, with the filament (or middle appendage) between them pointing backward. Silverfish do not have wings; they move by using their legs in a wiggling motion that resembles a swimming fish. Silverfish can run quickly on horizontal surfaces but are not as fast when moving vertically. However, they are able to jump up to a foot in the air.

Silverfish grow from egg to nymph to adult. The female lays up to three white, oval-shaped eggs in a crack or crevice. When the eggs hatch — which can vary from a period of three to six weeks depending on temperature — pale nymphs emerge. These nymphs continue to grow into adulthood, molting as they do and developing scales that are dark, shiny, and silver-colored.  The normal lifespan of a silverfish is between two and eight years. Silverfish reproduce at all times of the year, with the female laying about 100 eggs over the course of her lifetime.

What are the unique characteristics of silverfish?

Silverfish seek out food sources that have high sugar, starch, or protein content. They are attracted to carbohydrate-rich products like bread, flour, oats, and cereal, as well as meats and dead insects. They feed on glue and paper items — including wallpaper, photographs, and book bindings — and fabrics like cotton, rayon, silk, and linen. Silverfish also feast on dandruff, molted skins from insects, and mold, and can survive without eating for months. Telltale signs of a silverfish infestation are irregular chewing marks, molted skins, yellow marks, scales, or feces.

What are the habits of silverfish?

Silverfish avoid light, hiding during the day and seeking out food at night. If disturbed, they will scurry away in search of a dark space to hide. Silverfish are solitary creatures who search for food individually. However, large groups of silverfish can be found in a food-rich environment.

Where are silverfish commonly found?

Silverfish prefer cool to moderate temperatures with high humidity. They are often found in cabinets, closets, basements, storage areas, bathrooms, kitchens, laundry rooms, behind furniture, and between the pages of books. Once they find a source of food, silverfish tend to stay in the vicinity of that source.

What are the risks of a silverfish infestation?

Because they are adept at hiding, silverfish can grow in numbers before being discovered, resulting in a significant infestation. These pests do not bite or directly cause harm to humans or pets, but they are destructive to your home. Silverfish can contaminate foods and eat through fabrics, paper, or other items.

Silverfish eat mold, so their presence may also indicate a mold issue in your home. They are also a preferred food of spiders, centipedes, and other insects, so silverfish in your home may attract these pests.

Treatment

DIY Silverfish Treatments

Should you identify the presence of silverfish in your home, these do-it-yourself solutions may give you some relief:

  • Trap silverfish using a glass jar. Place a starchy food like bread inside the jar to attract the silverfish. Wrap the outside of the jar with masking tape to give the pest traction to climb. Once inside, the silverfish cannot climb back out of the slick glass walls. This approach will remove silverfish, but not their eggs or those insects who don’t climb into the jar.
  • Use purchased baits. Baits attract silverfish to a sticky surface which prevents them from moving. Like traps, baits do not treat the cause of a silverfish infestation.
  • Apply diatomaceous earth. This desiccant removes moisture, ultimately drying up the silverfish. While not toxic, diatomaceous earth is a lung irritant and should be handled very carefully.
  • Use chemical treatments. Powders and sprays containing boric acid, pyrethrins, or pyrethroids are effective at repelling silverfish. However, these compounds should not be used in areas where pets or children are likely to come into contact with them.

Often, destruction done by silverfish is attributed to moths or other insects, allowing the real culprit to continue to reproduce until discovered. A professional pest control service can discern the source of damage and treat appropriately and effectively.

Prevention

How to Prevent Silverfish

Like most insects, silverfish seek out a comfortable environment with plentiful food sources. The following measures can help to decrease the likelihood of a silverfish infestation:

  • Reduce the humidity in your home by repairing water leaks, ventilating moist areas, or using a dehumidifier.
  • Clean, vacuum, and mop regularly to remove food scraps, mold, paper, and silverfish eggs. Don’t overlook the interiors of cabinets, baseboards, and areas behind the stove and refrigerator.
  • Store food in airtight containers.
  • Avoid leaving out uneaten pet food.
  • Fill cracks that could serve as potential entry points with caulk or sealant.
  • Repair wallpaper that has pulled away from the wall. 
  • Place important papers and photographs in sealed containers.
  • Avoid creating stacks of newspapers or magazines.