What Kind of Bug Is This? Common Bug Groups

Is It a Silverfish? How to Tell Silverfish From Look-Alikes

Silverfish: 5 marks to check, what they are often confused with, whether they bite or sting, and where they turn up, quoted from university entomology and IPM sources.

These pages help you narrow a bug down to its group from what you can see. They are not medical advice. Seek medical care promptly for severe symptoms or any sign of an allergic reaction.

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At a glance

Group: Order Thysanura (as stated by this source; note the sources checked did not use the alternate/modern order name)
Body plan: Silverfish are slender, wingless, soft-bodied insects with 2 long, slender antennae; the body tapers from front to rear into 3 long, thin, tail-like appendages; adults and large nymphs are covered in delicate, dust-like scales.
Size: Common silverfish are about 1/2 inch long, growing as long as 3/4 inch.
Bites or stings: Not covered by the sources we opened; handle unknown bugs with care.
Where you find them: Silverfish desire cooler temperatures and are usually found in basements; firebrats prefer warmer temperatures (over 90°F) and are often near furnaces, hot water pipes, attics, and roofing shingles.

How to tell it is one of the silverfish

Silverfish have silvery-metallic scales covering the body, with antennae as long as the body, growing to about 12 mm.
Firebrats (a closely related, often-confused species) have tufts of brown scales giving a mottled appearance, with antennae longer than the body.
Color is the simplest field distinction: silverfish are shiny silver/pearl gray, while firebrats are shiny mottled gray or brown.
Body scales are an age-dependent clue: small nymphs (under about 1/8 inch) lack scales, while large nymphs and adults have them.
Silverfish/firebrat feeding damage is scraping, not biting, due to very weak mandibles — useful for identifying their damage on paper.

Often confused with

People most often mix silverfish up with:

firebrats

Open the other page and compare its list against the marks above; the differences are usually in the antennae, wings or the way the body is divided.

Pest or beneficial?

Silverfish and firebrats are mostly a nuisance pest that can destroy cereals, books, papers, wallpaper, and other starchy items via their feeding, but they do not feed on wool or other animal products.

Where they turn up

Silverfish desire cooler temperatures and are usually found in basements; firebrats prefer warmer temperatures (over 90°F) and are often near furnaces, hot water pipes, attics, and roofing shingles.

How to photograph it for identification

Get as close as your camera will focus, from directly above, in daylight or a bright lamp. Include the whole body with the legs and antennae in frame; a second shot from the side shows wings and body segments. Put a coin or ruler next to it for scale. For a bite or a bug found on skin or bedding, photograph the bug itself, not the mark. The app names the likely group; use the list above to confirm.

FAQ

Do silverfish bite or sting?

The sources we opened for this group do not describe bites or stings. Treat any bug you cannot identify with care and avoid handling it bare-handed.

What is the quickest way to recognize silverfish?

Silverfish have silvery-metallic scales covering the body, with antennae as long as the body, growing to about 12 mm.

Are silverfish a pest?

How do I tell silverfish from firebrats?

Color is the simplest field distinction: silverfish are shiny silver/pearl gray, while firebrats are shiny mottled gray or brown. Body scales are an age-dependent clue: small nymphs (under about 1/8 inch) lack scales, while large nymphs and adults have them. Silverfish/firebrat feeding damage is scraping, not biting, due to very weak mandibles — useful for identifying their damage on paper.

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