Silverfish in the San Gabriel Valley
Silvery, teardrop-shaped and quick — silverfish love damp, dark storage. Here's how to identify them and what draws them in.
- Silvery-grey, teardrop shape, about 1/2 inch
- Wriggle like a fish when they move
- Three long tail bristles
- Eat paper, starch, stored goods
- Active at night, very fast
What they look like
Silverfish are unmistakable: small (about 1/2 inch), silvery-grey, teardrop- or carrot-shaped, with three long bristles at the tail and two long antennae. They move with a quick, fish-like wriggle, which is how they got the name.
A close cousin, the firebrat, looks similar but is mottled grey-brown and prefers hot spots like attics and the area around water heaters. Both are wingless and very fast.
Silverfish fast facts
| Detail | |
|---|---|
| Looks like | Silvery, teardrop, 3 tail bristles |
| Where found | Damp, dark: baths, attics, storage |
| What they damage | Paper, books, starch, dry goods |
| Active when | Night; fast and shy |
| Concern level | Harmless to people; damages goods |
Where they live
Silverfish crave humidity and darkness. They hide in bathrooms, kitchens, laundry rooms, garages, attics and storage boxes — anywhere damp and undisturbed. In SGV homes they often turn up in bathroom cabinets, around plumbing, and in stored paper and cardboard.
They feed on starches and sugars: paper, book bindings, wallpaper paste, cardboard, dry goods, and natural fabrics like cotton and silk.
Signs of a silverfish problem
Beyond seeing the insects darting from a disturbed box or sink, watch for their feeding damage: irregular holes, notches and grazed surfaces on paper, book pages, wallpaper and stored documents. Yellowish stains, tiny pepper-like droppings, and shed skins are also common.
Because they're nocturnal and fast, you often find the damage before you ever see the silverfish.
How silverfish are controlled
Silverfish are a humidity problem first. The most effective steps are drying things out — ventilation, fixing leaks, running a dehumidifier in damp rooms — plus storing paper, books and dry goods in sealed containers and de-cluttering hiding spots. That alone resolves many light cases.
For persistent activity, a targeted treatment of the cracks and harborage where they live does the rest. Our DIY-vs-pro guide can help you gauge which situation you're in, and since they share damp pantries and storage with pantry pests, it's worth checking for both. Ask us for a free quote if it keeps up.
Related Pests
Quick Answers
Quick Answers.
Are silverfish harmful?
Silverfish don't bite, sting or carry disease, so they're harmless to people and pets. The damage they cause is to belongings — paper, books, wallpaper, dry goods and natural fabrics — rather than to your health.
Why do I have silverfish?
Silverfish follow humidity, so they show up where it's damp and dark — bathrooms, around plumbing, attics, garages and stored boxes. A leak, poor ventilation or stacks of paper and cardboard give them everything they need.
How do I get rid of silverfish?
Start by drying things out — ventilation, fixing leaks, a dehumidifier in damp rooms — and store paper and dry goods in sealed containers. For persistent activity, a targeted treatment of the cracks and harborage where they hide finishes the job.
Where do silverfish hide?
They tuck into dark, humid, undisturbed spots: bathroom and kitchen cabinets, around pipes, in attics and garages, and inside stored boxes of paper, books and fabric. They're most active at night.
Do silverfish lay eggs in the house?
Yes — in humid, hidden spots they can reproduce indoors, which is why a damp problem left alone tends to grow. Lowering humidity and removing clutter cuts off both their food and their breeding sites.
How do I keep silverfish out of stored books and papers?
Keep humidity down and store books, documents and keepsakes in sealed plastic bins rather than cardboard boxes, ideally somewhere dry rather than a damp garage or attic. Silica gel packs in the bins help hold moisture down.
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