What Is a Silverfish Insect? Identifying NZ's Living-Fossil House Pest

The silverfish insect is one of the most ancient creatures you'll find in a New Zealand home — a wingless, silvery scavenger that has barely changed in 400 million years. Whether you've searched "silverfish insect", "silver fish insect" or even "insect silver fish", you're looking at the same animal: Lepisma saccharina, the common silverfish.

Here's how to identify the silverfish insect, tell it apart from look-alikes, and understand why it turns up in Kiwi homes.

What is a silverfish insect?

The silverfish insect is a wingless, teardrop-shaped insect covered in fine silvery scales. It grows to 10–20 mm, tapers at the rear into three long bristle-like tails, and has two long antennae sweeping forward from the head. When disturbed it moves in a quick, darting, fish-like scuttle — which is exactly how it got its name.

Silverfish belong to the ancient insect order Zygentoma. They never had wings, even hundreds of millions of years ago, which makes them genuine "living fossils" — contemporaries of the earliest insects, still thriving in our bathrooms today.

How to identify a silverfish insect

• Shape: wingless, teardrop-shaped, tapering at the rear with three tail bristles.
• Colour: silvery-grey and metallic, covered in fine scales.
• Size: 10–20 mm as an adult.
• Movement: a quick, darting, fish-like scuttle when disturbed.
• Signs: shed silvery skins and tiny black peppery droppings in dark corners.

"Silver fish insect" or "insect silver fish" — is there a difference?

No. "Silverfish insect", "silver fish insect" and "insect silver fish" all describe the same species. The name refers to the silvery scales and the fish-like movement — there is no separate "silver fish" insect in New Zealand homes. If you see a silvery, darting, wingless insect indoors, it's a silverfish.

Is the "silverback bug" a silverfish?

"Silverback bug" is a slang name some Kiwis use for the silverfish insect, but silverfish aren't true bugs at all. True bugs belong to the order Hemiptera (aphids, cicadas, shield bugs) and have piercing mouthparts; silverfish are in Zygentoma and chew their food. So while "silverback bug" usually means silverfish, the animal is a primitive wingless insect, not a bug.

What do silverfish insects eat?

Starch and cellulose: paper, book bindings and glue, wallpaper paste, photos, cardboard, cereals, flour, pasta, and natural fibres like cotton and linen. In a New Zealand home that means books, paperwork, stored clothing and pantry food are all at risk — though silverfish don't bite or spread disease.

Where do silverfish insects live?

Silverfish love dark, damp, undisturbed places. In Kiwi homes that means bathrooms, laundries, roof spaces, under sinks, inside wardrobes, behind skirting boards and in stacks of old papers and cardboard boxes. They're nocturnal, so you'll mostly see them at night when you switch on a light.

Silverfish insect FAQ

Is the silverfish insect harmful to people?

No. Silverfish don't bite, sting or carry disease. The harm is to belongings — books, papers, photos, wallpaper and stored clothing — not to your health.

How long do silverfish insects live?

Surprisingly long for an insect: a silverfish can live two to eight years in the right conditions, and unlike most insects it keeps moulting throughout its adult life, which is why you find their shed skins.

How do I get rid of the silverfish insect?

Dry out damp rooms, remove their starchy food and hiding spots, and set a reusable baited trap in the dark corners where you see them. You can read the full removal guide in our silverfish control article.