Introduction to Silverfish

Silverfish in Your House

Silverfish adult.

Silvery Silverfish and Nocturnal Munchies

If you're like me, you get up in the middle of the night to either go to the kitchen to grab a bite, or hit the bathroom. Now, usually I avoid turning on the light, but sometimes you just have to. It's then that you see the quick silvery flashes of insects moving like those dragons you see at the Chinese New Year, back and forth scuttling quickly for their lives. Those are silverfish (Lepisma saccharina), and in this post we'll explore exactly what silverfish are, why people don't really like them, and a few ideas for helping secure your home from them.


I think it's funny when pages start off describing silverfish as looking silvery and scaly like a fish. I just don't see it. I've been in outdoor education for years and it's just not evident to me, but you see that description on all the web pages you search on. I think silverfish look more like grayish miniature mummy sleeping bags with antennae on their heads and bristles on their butts.

Silverfish scuttle really fast and move back and forth like those dragons I mentioned. Now to be fair, they're really not that big, usually they range of 1/2"-1" long stem to stern. That doesn't mean that they won't frighten the holy bejezus out of you when you turn on the light at 1 a.m.!All silverfish, and their cousins the firebrats (great name eh?), are nocturnal. This is why you usually don't see them during the day. They're also afraid of light, like the Gremlins in the old 80's movies, more on this later.

Adult silverfish (Photo: Flicker Sharing, Chris)

If you look closely you'll see that they have six legs, a tapered body, three butt spines, and two antennae. There's a largish bump where it's main body or thorax is. You can also take a deep breath because they don't have wings, so they can't fly, and they're really only able to crawl on the floor. They can't climb walls or vertical surfaces (yeah for that!). You can also breathe a sigh of relief because they are not venomous, they don't bite, and they're not dangerous to people. Silverfish also don't carry diseases.


Scientists like to be cheeky when they name things, and sometimes they're quite literal. In this case the silverfish's Latin name gives away what they eat, Lepisma saccharina. Do you see it? saccharina refers  to what they like to eat, saccharides or sugars. They're not so different from us, they're animals with a sweet tooth. However, their sweet tooth includes a lot of "sugars" that we'd find awful. For instance, we like our chocolate bars and ice cream with disaccharides (double sugars), which makes them sweet. Silverfish would scoff at this and call us picky eaters. They eat any saccharide, including the starches and carbohydrates found in things like  carpet fibers, books pages, wallpaper paste, and more. The little wee starch fiends pig out on the stuff we like to have in our houses, using their sharp mandibles to chew through our favorite books, carpets, cardboard, and even some clothing such has linen and rayon. You can sometimes tell they've been there because they leave lovely little yellow waste stains behind too.

Here's the rub, they like dark cool places, without light, lots of starches and carbs to chew on, and for it to be fairly moist (there I said it, moist, a horrible word but necessary here). This pretty much describes every basement and bathroom without windows you can think of. They can also be found in attics, or places with 75%+ humidity.

NOTE: if you find something that looks like a silverfish but it's in a dry and warm place, then it's probably their cousin the firebrat (Thermobia domestica). They eat similar things and do similar damage, but in warm, dry places.

Silverfish (Photo: Flicker Sharing, Masenot)


As a naturalist I like to flip the script and see the positive in all animals and creatures. For humans, we find silverfish to be officially "pests" because they damage stuff we like or want to keep. However, in nature they play an important role as decomposers, breaking down plant matter, dead trees, organic leaves, and materials. In fact, they're sort of like nature's composters. Unfortunately, they're composting your favorite photo albums and books too when they're inside.


If you want to get rid of silverfish, then you have to stop giving them the right conditions to live in as roommates. Here's a checklist of things to try:

  1. Get rid of the damp and moist conditions, if it's dry they don't like it. Use a dehumidifier, box fans, or exhaust fans in bathrooms (especially after you shower).
  2. Seal up cracks where they might get in, especially cracks in basement walls, door frames, and garage doors. Use non-attractive stuff, like putty or caulking.
  3. Vacuum regularly, and clean out the cracks and crevices where they may hide.
  4. Get stuff off the floor. They can't climb,
  5. Put stuff in clean and tight bins that are secure and dry.
  6. Illuminate the area, get as much light as you can into the space, and provide air circulation. They don't like light, so make it shine!

If these measures don't work, then you can always try over-the-counter methods such as boric acid (Terro). Boric acid is the same stuff they use to feed ants so you could use ant traps too. PLEASE DO NOT USE STICKY TRAPS. I can't stress enough not to use sticky traps. I've worked with many wildlife rehabilitators, and I've had to remove so many suffering animals caught in sticky traps, or end their suffering. I've seen everything from hummingbirds, baby mice, bats, and harmless snakes stuck in them. They are a cruel and slow death, and often catch animals they aren't aimed at.

if worse comes to worse, then call your local pest company, but make sure they use non-toxic materials, and those safe for pets. Remember, silverfish like carbs and saccharides, but so do pets in many cases.

Silverfish are the tiny mummy-sleeping-bag-Chinese-dragons that love starches in our basements and bathrooms. Even if you don't want them around, maybe you can appreciate how perfectly they're made for slipping into small tight spaces and breaking down the materials that nature says need to be "composted" for the forest floor. With a bit work you can make your home safe and secure from these unwanted house guests.