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What to Know About Silverfish

Silverfish aren’t known to carry pathogens or other potentially damaging diseases.

What Are Silverfish and Can They Hurt You?

Silverfish are translucent, multi-legged insects that can scare the you-know-what out of you when found in your home. The good news is they won’t bite you — but they can cause significant damage to things like wallpaper, books, clothing, and food.

Here’s what you should know about these silvery pests that move like fish, including how to evict them from your home.

Silverfish belong to the species Lepisma saccharina. Entomologists believe silverfish are the descendants of insects that date back millions and millions of years. Other names people may use for silverfish include fish moths and bristletails because of the three long appendages at the end of their bodies.

Additional key aspects to know about silverfish include:

They’re very small, usually about 12 to 19 millimeters in length.
They have six legs.
They’re usually white, silver, brown, or some combination of these colors.
They like to live in humid conditions and usually only come out at night.

Scientists don’t believe silverfish bite people, as the insects have very weak jaws. They aren’t really strong enough to pierce a human’s skin. Some people may mistake an insect called an earwig for a silverfish — earwigs can pinch your skin.

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Silverfish do bite into their food sources, though. Because their jaws are weak, it’s really more like a long drag or scrape. That’s where silverfish can damage your house. They can scrape their teeth against things like wallpaper, fabric, books, and other paper items. They tend to leave a yellow residue (fecal matter) in their wake.

Because silverfish are nocturnal and actually rather elusive, seeing these yellow markings or damage on paper or fabric in your house is usually the first sign that you have these insects.

Silverfish do leave behind their skin as they age — a process known as molting. These skins can collect and attract dust, which can trigger allergic reactions in some people.

An older 2008 laboratory study found that silverfish may cause allergic-type breathing problems in people who were allergic to common indoor allergens, but there aren’t enough additional studies to confirm this.

Do silverfish crawl in ears?

This question stems from a rather unpleasant rumor that silverfish crawl into your ear and eat your brains or lay eggs in your ear canal.

Good news: They don’t do any of this. Silverfish are essentially very shy to humans and are really trying to avoid you at all costs. They don’t eat blood and are more interested in your paper products than anything on your body.

Are silverfish harmful to pets?

Just as they can’t bite humans, silverfish can’t bite pets. They won’t poison your pet if they eat them. But eating silverfish could give your dog or cat an upset stomach, especially if you have an influx of them.

What to Know About Silverfish

Silverfish are pests commonly found around the world. They are harmless insects, but they can infest your home.

What Are Silverfish?

Silverfish are shiny silver insects with scales and antennae. They don’t have wings, but they have a soft body and are covered in fine scales that look like a fish.

They have a flat and oval-shaped body. Adults are usually about ¾ inch long with two antennae and 3 tail projections. A firebrat is a similar insect, but it is usually darker and mottled grey.

Silverfish like the dark. They hide during the day and avoid direct sunlight. If you move an object they are hiding in or under, they will dart out and find another dark hiding place.

Female silverfish lay eggs constantly after reaching the adult stage. They lay eggs in crevices and cracks around your home, which hatch within 3 weeks. Young insects reach the adult stage within 4 to 6 weeks.

Young silverfish look like adult silverfish, only smaller and white. These insects live a long life, anywhere from 2 to 8 years. They can also survive a long time without food, sometimes up to a year. However, they are sensitive to moisture and need high humidity to survive.

Silverfish grow in damp, dark, and cool places. Large populations can grow in new buildings with wet brick and stone. You might also commonly find them in:

Basements
Sinks
Bathtubs
Closet shelves
Behind baseboards
Bookcases
Behind windows
Behind door frames

What do Silverfish Eat?

Silverfish and firebrats are chewing insects and general feeders. They eat carbohydrates and protein, including:

Flour
Rolled oats
Dried meat
Paper
Cardboard
Books
Glue
Vegetables
Cereals
Dead insects

Sometimes they can enter into a new home in cardboard cartons, boxes, papers, and books that come from infested places.

Are Silverfish Harmful?

These insects are generally nuisance pests. They won’t hurt you, but they can contaminate your food. Silverfish leave their poop behind in your food, so make sure to check for any insects. Discard anything that has bugs in it.

How to Get Rid of Silverfish

Silverfish are as common as cockroaches in some states. It can be very difficult to manage an infestation and it’s usually best to use the following methods together for the best results.

Seal your food. Reduce food sources for the silverfish and keep all food sealed in airtight containers.

Vacuum regularly. Keep food in one area of the house only. Vacuum carpets, floors, and furniture regularly and clean up any food debris.

Dehumidify and get rid of water. Silverfish love humidity and water. Reduce water sources by using a dehumidifier in the basement. Keep showers, tubs, sinks, and your laundry room clean and dry. Use plastic sheeting on the ground in any dirt crawl spaces and attics.

Make sure your yard is properly landscaped to allow water to drain away from your house. Keep your house in good repair with good window seals and caulking in cracks.‌

Fill cracks. Silverfish lay eggs in cracks and crevices. Seal off any cracks in your home to stop them from laying eggs and from hatching.

Use dusts in uncommon areas. Dusts like diatomaceous earth, boric acid, and amorphous silica gel are insecticides. Sprinkle these in areas where you normally don’t go like crawl spaces and attics. You can spray dusts like boric acid into cracks. These dusts only work if they stay dry.

Use combination insecticides. Residual sprays like propoxur, chlorpyrifos, and bendiocarb can protect your house for up to 45 days. You can spray these in infected areas and follow up with pyrethrins. These are short-contact sprays that will irritate the bugs and send them into the residual spray. Focus on cracks and places where you often see the bugs.

Japanese cedar essential oil. This essential oil (Cryptomeria japonica) might help control silverfish.

Remember that insecticides are poisonous and toxic to the environment. Read the labels and follow directions closely. Keep any products away from children and pets. Contact a professional pest control company to help deal with major infestations.

Show Sources

Pennsylvania State University: “Bristletails (Silverfish and Firebrats).”

Texas A&M University: “Silverfish.”

‌University of Florida: “silverfish – Lepisma saccharina.”

‌University of Nebraska: “Silverfish and Firebrats (005).”‌

What to Know About Silverfish