- Common silverfish
- 10–12 mm, silvery, carrot shaped
- Long-tailed silverfish
- Up to about 19 mm, grey, long tail bristles
- Active
- At night
- Peak season
- All year
A larger relative, the long-tailed or grey silverfish, has spread across the UK and is now common in newer, drier homes. It's less dependent on damp, which makes it harder to shift.
Signs of silverfish
- Small silvery insects darting away when you switch on a light, often in bathrooms
- Irregular holes or grazed patches on paper, wallpaper, books or photographs
- Tiny pepper-like droppings in drawers and on shelves
- Grey silverfish in living rooms or bedrooms of newer homes, not just bathrooms
How to be sure
Both have three long bristles at the tail and a tapering body. Common silverfish are shiny silver and stay in damp rooms. Long-tailed silverfish are larger, greyer and turn up in dry rooms too.
What you can do yourself
- Reduce humidity: use extractor fans, open windows after showers, fix leaks and use a dehumidifier if needed.
- Clear piles of paper, cardboard and old magazines, especially from floors.
- Seal cracks along skirting boards, around pipes and in tiling.
- Use silverfish gel bait in cracks where you see them. Bait is especially important for long-tailed silverfish.
- Vacuum along skirting edges and inside cupboards regularly.
Call a professional if
- You have long-tailed silverfish throughout the home
- Baits and humidity control haven't helped after a month or two
- You store valuable papers, books or collections
Keeping them out
- Store important papers and photos in sealed plastic boxes
- Keep humidity below about 50% in problem rooms
- Avoid storing cardboard boxes directly on floors
Kit that helps
- Silverfish gel bait
- Dehumidifier
- Sealant for skirting gaps
- Airtight storage boxes
Product types only. We'll only ever point you to things we'd use ourselves.
Questions people ask
Are silverfish harmful?
They don't bite or sting and aren't known to spread disease. The damage is to paper, books and some fabrics.
Why have I got silverfish in a brand-new house?
New homes can hold moisture as they dry out, and long-tailed silverfish arrive in building materials and cardboard. Bait plus time usually sorts it.
Do silverfish mean I have damp?
Common silverfish often do point to high humidity. Long-tailed silverfish can thrive without damp.