What Are Silverfish? Everything you need to know about them.

We recently found lots of silver creepy insects in our bathroom and were wondering what they were. So we did some research and here is what we found out.

So, what are silverfish? Silverfish are small insects that have legs and no wings. They are silvery or gunmetal in color and have two noticeably long threadlike antennas. Adult silverfish are about 12-19 mm long and have a flat and oval body shape and are often compared to shapes like a teardrop or carrot. They thrive on a diet based on protein and polysaccharides, which is a biochemistry term for carbohydrate (e.g. starch, cellulose, or glycogen). 

To help get to know what these pests are, we have outlined some more information below on what silverfish look like, their lifecycle, where they live, what they eat and how you can get rid of them.

What do Silverfish look like?

So, what are silverfish and what do they look like? Silverfish are small insects that have legs and no wings. They are silvery or gunmetal in color and have two noticeably long threadlike antennas. 

Adult silverfish are about 12-19 mm long and have a flat and oval body shape and are often compared to shapes like a teardrop or carrot. 

At the tail end of their abdomen, silverfish have three tail-like limbs that resemble their two antennae. They move in a wiggling motion that resembles the movement of a fish.

Silverfish are generally nocturnal insects and feed on a diet that consists of carbohydrates such as sugar or starches. 

Younger silverfish look similar to adults, but are whitish in color are noticeably smaller in size (about 1-6mm) and lack the noticeable appearance of scales until they reach their adult stage. 


The table below compares what both an adult and young silverfish look like.

Adult Silverfish


10-18 mm long

Adult Appearance:

  • Silver to brown in color
  • 6 legs
  • Two antennae 
  • Oval and elongated in shape 


  • 3-8 year lifespan at this stage

Young Silverfish


1-6 mm long

Immature Appearance:

  • White in color
  • 6 legs
  • Two antennae 
  • Oval and elongated in shape


  • 18-months – 3 years at this stage

Silverfish Eggs


1 mm long and 0.8 mm wide

Immature Appearance:

  • Oval in appearance
  • Smooth surface,
  • cream colored to yellow-brown


  • hatches in about 2 months

What is the lifecycle of silverfish?

Silverfish breed and mature slowly relative to other insects and also live longer than most insect species. A silverfish will generally live for up to 8 years and in that period a female will lay around 100 eggs and deposit them in groups of 1-4 eggs at a time.

They deposit eggs in cracks around the inside of a home or attic, making them difficult to find and unlike some other insects, silverfish can produce eggs all year.

An egg will take between 2 weeks and 4 months to grow. They are hemimetabolous insects, which means they develop through three stages:

  1. Egg: Depending upon climate conditions and species, eggs may take between 19 to 60 days to hatch. Humid conditions are preferable, though silverfish can thrive in almost any environment.
  2. Nymph: When they emerge from the egg, silverfish nymphs are miniature versions of the adults. They go through a number of molts during development and continue to molt throughout their lives. Some species may undergo more than 50 molts.

Adults: Typically, silverfish become adults in about three or four months. In cool climates, it may take up to two years to develop into a mature adult. Unlike most insects, silverfish don’t change appearance or characteristics throughout their lives they have only grown in size and they have a gradual growth through molting.

The time they spend at each stage of their growth cycle depends on temperature and access to nutrition, but it is assumed that they may develop to adults within 18 months in the right conditions. 

Where do Silverfish live?

Silverfish require warm temperatures and high humidity and no light to thrive. So they prefer to remain hidden most of the time. They tend to live, lay eggs and hide in small cracks and crevices in rooms and furniture. As for the rooms where you might find them, that all depends on whether the environment is right like the temperature, humidity, and food sources.

Also check the walls and shelves in your basement, laundry room, garage, and storage areas. The kitchen can also offer a lot of hiding places with cupboards, bookcases, closet shelves, baseboards, etc. Don’t forget to check the window and door frames as well.

That’s for the silverfish in houses but there are also outdoor places where they can live and hide – under rocks and tree bark, leaf mold or other insect’s ants’, and birds’ nests.

If you’re worried about any damage that silverfish may have done, check very closely where you may store your books or in your bathrooms. Here are a few suggestions on where to check for damage:  

  • Check your bookshelves and documents: Grab a magnifying glass and look in hidden areas on your bookshelves and within books, Make sure to look in other areas where paper-based documents might be located especially when these items are stored in a moist room of the house. If you have a home office, you may want to store your important documents in hard plastic sleeves or plastic containers.
  • Check your bathrooms: Bathroom hiding spots such as around the bathtub, the plumbing or below the sink. Scan the bathroom floor and surfaces. Have a look around where your toothpaste may be as this is an ideal food source.
  • Check your wardrobes and closets: Silverfish also like to eat natural fabrics like silk, linen, and cotton. They love the glues used in synthetic fibers and starches used to press clothing, this is a great source of carbohydrates for them. If you’re seeing silverfish in wardrobes, closets or drawers, you should definitely move your clothes to a safer location.

Now you have seen some damage from silverfish in your home planning to prevent silverfish in your house is the key to helping your house remain silverfish free and to ensure any future silverfish infestations.

What do Silverfish eat?

Silverfish thrive on a diet based on starch, carbohydrates, and protein. They require protein to grow and are unable to fully develop without it. 

You can find them snacking on anything from paper, grain or sugar, but even minor leftovers such as fat, breadcrumbs, cereals, and seeds.

Silverfish may move long distances to find food, but if a good source is encountered they tend to remain in the vicinity of it. They have also been known to be cannibals if food sources are scarce. They can also last long periods without food.

For more information on what silverfish might be eating in your home, check out our other blog post on what silverfish eat.

Silverfish feed on lots of different products and materials in your home and often get into your house by hitching a lift on or in something or by crawling through cracks and crevices in search of food. 

Their diets are fairly simple and they eat protein-based items and carbohydrates. Below is a list of where you might find silverfish in your house and what they might be feeding and eating on with some useful tips for protecting your home and possessions from them:

Kitchen Living room Bathroom Bedroom
  • cereal
  • flour
  • grains
  • pasta
  • Beans
  • Pet hair
  • dry pet food
  • Wallpaper
  • Books
  • curtains, 
  • Carpets
  • Linen 
  • Cotton
  • Pet hair
  • shampoo
  • Human hair 
  • dandruff
  • cotton 
  • damp clothing
  • toothpaste
  • cotton
  • linen
  • silk
  • rayon
  • Stained clothes 
  • Starch on clothes
  • Human hair
Helpful Tip: Store dry goods in air-tight plastic containers. Helpful Tip: Keep valuable books in a dry room don’t forget to vacuum Helpful Tip: Control humidity by using bathroom fans and turn it on after showers or baths. Helpful Tip: Store valuable clothing in sealed packages or containers.


How to get rid of silverfish

So know you’ve learned how to spot the signs of silverfish eating your books, documents, and photographs as well as prevent silverfish but what if you find them – how can you go about getting rid of them.

To help get rid of silverfish in paper and books we’ve outlined how you can do just that when you find them in books and paper as well as the best ways to get rid of them when you find them in your bookshelves and draws.

Below are our top tips on how to get rid of silverfish:

  • Don’t be afraid to use chemical-based control methods to kill of any remaining silverfish or eggs in and around your bookshelves, drawers, and rooms you found the silverfish within. 

This is one of the most effective ways to remove silverfish and silverfish eggs is to use silverfish insecticide sprays. Just make sure you don’t apply them to your documents or books. 

However, not every insecticide spray is fit for all silverfish eradication purposes, which is why you should no which spray is best for your specific situation. That is why we have created a guide on the best sprays for getting rid of silverfish here.

  • Once you have used an insecticide spray or powder to get rid of any silverfish, place a number of traps in and around the bookshelves and corners of the rooms to trap any remaining silverfish and to establish whether you have gotten rid of the silverfish from your DIY extermination methods.
  • If you can’t get a handle on it and these pesky insects keep appearing, you may feel you need professional help from a pest exterminator. 

If this is the case, be sure to check out our complete guide on how to choose a pest exterminator and make sure you are hiring the right professionals.

Well there you have it, lots of food for thought on what silverfish actually are and what you can do about it today to prevent any problems and stop this from happening in your home and making sure your most prised paper-based possessions don’t get destroyed.

If you’d like to understand how silverfish in a little more detail and how you can make sure they aren’t a problem for you at any point make sure you check out our complete guide here on how to get rid of silverfish in your home for more tips and suggestions.

Related Questions:

Are Silverfish Harmful? No, Silverfish are not a harmful pest, they are more of a nuisance. Left unchecked they can do damage to your home. They love paper, so keep all your documents and photographs safe if you spot signs of silverfish. 

What are silverfish a sign of? Silverfish are a sign of a possible infestation that needs to be dealt with. They thrive in unclean, humid and high-temperature homes so be sure to keep your house as tidy as possible and the environment controlled enough to not allow silverfish to thrive.

Can you find silverfish in your bed?

Yes, you can find silverfish in your bed. Your bed is a place silverfish may look to explore for possible food sources like hair, dead skin or even the material that your bed sheets and clothing are made out of.


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