Silverfish: All You Need to Know

Silverfish are named for their fish-like shape, silver color, and swim-like motions. They are a type of insect pest found all over the U.S., including here in the Pacific Northwest. According to Pest World, they are mainly a nuisance pest, versus a physical threat, but their “creepy” appearance makes the presence of them in your home concerning. In this guide to silverfish, we answer common questions about these occasional invaders, provide silverfish prevention tips, and list options for getting rid of them.  

6 Common Questions About Silverfish 

#1: What does a silverfish look like? 

In the introduction, we mentioned that silverfish look creepy, but what does that mean? Check out our pest library for more details about silverfish and other common Portland-area pests. Here is some basic information to help you identify silverfish:

  • Size: ¼ – 1” (the size of a nickel)
  • Color: Silver-grey, covered in shiny scales 
  • Body composition: A head, thorax, and abdomen with six legs, two compound eyes, two long antennae, and three rear bristles that resemble tails. The distinction between the thorax and the abdomen is tapered without a waist.
  • Body shape: Flat and narrow and tapers down from the head in the shape of a carrot
  • Unique identifiers: 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

#2: Are silverfish nocturnal? 

Silverfish are nocturnal insects that like to hide out from humans in tight cracks or crevices during the day. 

#3: Do silverfish bite? 

Silverfish do not bite humans or transmit diseases. Typically, when disturbed, a silverfish will quickly move to a safer location that is dark and quiet.

#4: What do silverfish eat? 

Silverfish prefer a diet that is high in sugar, starch, or protein. This means that carbohydrate-rich products like bread, flour, oats, and cereal, as well as meats and dead insects, are on the menu. But their diet can become problematic for humans because they feed on glue and paper items — including wallpaper, photographs, and book bindings — and fabrics like cotton, rayon, silk, and linen. Silverfish also eat mold, so their presence might signal a mold problem in your home or business.

#5: Are silverfish dangerous?

Silverfish do not directly cause harm to humans or pets, but they are destructive to your home or commercial property. They can contaminate foods and eat through fabrics, paper, or other items. If you have old photos or books that you are storing, silverfish may snack on them unless you protect your memories in sealed rubber or plastic containers. Silverfish are also a preferred food for spiders, centipedes, and other insect pests, so silverfish in your home may attract these pests.

#6: Do silverfish fly? 

Silverfish do not have wings, so they can’t fly. However, they are able to run very fast and are able to jump up to a foot in the air. Silverfish can move quickly on flat surfaces by wiggling their legs in a fish-like swimming motion. They move less quickly on vertical surfaces. 

House Centipede vs Silverfish: How to Tell the Difference

Silverfish and house centipedes are both considered creepy pests because they are both long, leggy, and strange in appearance. They also prefer similar living conditions – dark humid spaces. But they are, in fact, very different. Here are a few common ways to tell the difference between the two:

  • Antennae placement: Both have antennae on their heads, but silverfish also have three long limbs extending from their abdomen. 
  • Behavior: Centipedes can bite while silverfish don’t. 
  • Body shape: Centipede bodies are segmented while silverfish have flattened bodies.
  • Color: Centipedes are yellowish brown with bodies that are banded vertically with darker shades of brown. Silverfish are shiny and silvery grey with visible bands or stripes.
  • Eating habits: Centipedes are carnivores and eat other small insects while silverfish like to eat starches and sugars and feed on fabrics and paper. 
  • Number of legs: While silverfish have three pairs of legs, centipedes can have a significantly larger number.
  • Size: Centipedes are larger (up to 1½“ long) than silverfish (up to 1” long).  

A silverfish insect crawling on the floor in the shadows

How Do Silverfish Get Inside?   

Silverfish are frequently attracted to commercial places like offices and libraries due to the abundance of paper products, but they’re also commonly found in homes. Once they locate a stable food source, they tend to stay, especially if it’s in a damp area like a basement or attic.

Silverfish may also be inadvertently brought indoors by people. They hitch a ride on contaminated dry food items, boxes of books or paper, fabrics, and other items containing significant amounts of starch and sugar. People may accidentally purchase silverfish-infested products and can unknowingly transport these bugs into their living spaces.

One of the biggest attractants of silverfish is moisture. These nuisance pests require high humidity levels to survive, which is why you commonly see them in bathrooms, kitchens, crawlspaces, and other damp areas.

If you’ve dealt with a silverfish infestation or are doing some research on these nuisance pests, you may have come across the question: Do LED lights attract silverfish? The short answer is no. Silverfish enter homes or commercial properties in search of food and water. They prefer damp crawlspaces and damp attic or roof areas, dark closets, or bathrooms. 

Signs of a Silverfish Infestation

Keep an eye out for common signs of silverfish infestation including:

  • Seeing a live silverfish
  • Irregular chewing marks – holes in book bindings, linens, paper, and wallpaper
  • Molted skins and scales 
  • Yellow marks – dust that they leave on surfaces (e.g., books, cardboard boxes, papers)  
  • Feces – small, round, and black, resembling peppercorns

How to Get Rid of Silverfish

Silverfish are very good at hiding. This means they can grow quickly in numbers before being discovered, resulting in a significant silverfish infestation. The best way to get rid of silverfish is to prevent a silverfish infestation in the first place. Keep the following silverfish prevention tips in mind: 

  1. Seal cracks and repair home damage. Begin outdoors with siding, windows, and doors before addressing indoor damage.
  2. Minimize moisture. Watch for leaky water pipes and moldy wood that might attract silverfish. Use a dehumidifier if moisture is a concern.
  3. Cut their food supply. Even though silverfish can endure without food for a while, keeping damp areas free of paper products like cardboard, old books, and magazines can help eliminate them. Use plastic bins with secure lids instead of cardboard boxes in attics or basements. Store grains (flour, oats, etc.) in airtight containers to deter them from the kitchen.
  4. Use temporary vacuuming. Vacuuming can offer a brief solution to a silverfish invasion.

DIY treatment to remove silverfish is not recommended. You can purchase aerosols and dust from lawn and garden stores, but it’s important to read the label to make sure it is effective for treating silverfish. (For example, aerosol “bombs” are generally not effective.) Any pest control products should be applied by a pest control professional to minimize exposure to toxic chemicals. Integrated Pest Management (IPM) promotes prevention and elimination with insecticides as a last resort. Insecticides won’t work unless you also get rid of the dampness, food, and hiding spots that help these pests survive.

Silverfish Pest Control In Portland, Vancouver, Olympia, And Kelso

To eliminate silverfish in your home or business, it’s best to work with a local pest control company like Interstate Pest Management. Our dedicated team of silverfish exterminators will inspect your property, locate the silverfish infestation, and properly remove them. We specialize in environmentally conscious pest control in Oregon and SW Washington. If you want to get rid of silverfish for good, get in touch with us here or call us at (503) 832-4997. We proudly serve Kelso and Longview, Olympia, Portland, Vancouver, and all the surrounding areas.