Bug Identifier

Centipedes, Millipedes & Crawlers

Silverfish

Lepisma saccharina

048121620
Body length in millimeters. Shaded bar shows the typical adult range.
Scientific nameLepisma saccharina
GroupCentipedes, Millipedes & Crawlers
Size12–19 mm (up to about 0.75 in)
Colors Gray and White
Legs6 legs
WingsNo (as usually seen)
Where foundBathroom, Basement or garage and Bedroom or bed
Most activeSpring, Summer, Fall and Winter
BitesNo
StingsNo
Risk levelNuisance

How to identify it

The silverfish is a medium-sized member of the centipedes, millipedes & crawlers group. Wingless ground crawlers, many with far more than six legs. Check for these three features:

  1. Silvery-gray, teardrop-shaped, scaly body
  2. Three long bristles at the tail
  3. Fast, wriggling movement in bathrooms and basements

About this bug

A wingless, carrot-shaped insect covered in silvery scales that moves with a fish-like wiggle. It eats paper, glue, starches and fabrics in damp areas.

You'll usually find silverfish in the bathroom, in basements and garages and in bedrooms and beds. They are most active in spring, summer, fall and winter.

Is it dangerous?

Silverfish don't bite; they damage books, wallpaper and stored papers.

Our rating: Nuisance, meaning it is a nuisance pest but not a health threat to most people.

When you'll see silverfish

Silverfish are most active in spring, summer, fall and winter. In spring, overwintering adults become active and many species lay their first eggs. Summer heat speeds up development, so populations can grow quickly. In fall, many bugs look for shelter, and some move toward or into buildings. In winter, activity continues mainly indoors in heated spaces.

Typical places to check: bathroom, basement or garage and bedroom or bed.

About centipedes, millipedes & crawlers

The silverfish is one of the centipedes, millipedes & crawlers. This group gathers wingless crawlers that people often lump together: centipedes, millipedes, silverfish, earwigs, springtails, booklice and pill bugs. Most need high humidity to survive and dry out quickly in dry air.

Because moisture is the common thread, a dehumidifier and fixed leaks often do more than any insecticide.

What to do about it

  1. Run a dehumidifier to keep humidity below about 50 percent
  2. Store papers and photos in sealed plastic bins
  3. Apply boric acid dust in wall voids and behind baseboards

Bugs that look similar

House CentipedeScutigera coleoptrata25–35 mmNuisance

Size: House Centipedes are larger, reaching 35 mm, while silverfish top out around 19 mm.

EarwigForficula auricularia12–20 mmNuisance

Wings: Earwigs have wings, while silverfish are usually seen without them.

Frequently asked questions

What does a silverfish look like?

Silvery-gray, teardrop-shaped, scaly body. Adults measure 12–19 mm (up to about 0.75 in).

Does the silverfish bite or sting?

It does not bite. It does not sting. Silverfish don't bite; they damage books, wallpaper and stored papers.

Where do silverfish live?

Silverfish live in the bathroom, in basements and garages and in bedrooms and beds.

When are silverfish most active?

Mostly in spring, summer, fall and winter.