Silverfish control in Los Angeles

Silverfish and firebrats

• Silverfish are up to about half an inch long, silvery-gray and carrot-shaped, with long antennae and three thin “tails.” They move in quick, fish-like wiggles and prefer cool, humid places.
• Firebrats look similar but are mottled brown-gray and prefer warm spots — near water heaters, furnaces, dryer vents and hot attics.

Both are active at night and hide by day in cracks, wall voids, behind baseboards and inside stored boxes. They can live for years, so a small problem can build up slowly.

Signs of silverfish

• Silverfish trapped in sinks or bathtubs, where they can’t climb the smooth sides.
• Irregular holes, notches or surface grazing on paper, book covers, photos, cardboard and wallpaper.
• Yellowish stains, tiny pepper-like droppings or shed scales in drawers, shelves and boxes.
• Damage to starched or natural fabrics — cotton, linen, rayon — in closets and storage.

What attracts them in Los Angeles homes

• Bathroom humidity. Showers without a working exhaust fan, slow leaks under sinks and around tubs.
• Older plumbing and roofs. Leaks inside walls, around water heaters and under roof valleys keep framing and insulation damp.
• Crawlspaces and garages. Raised-foundation homes with damp soil underneath, and garages full of cardboard boxes.
• Paper and starch. Stacks of books, magazines, files and stored clothing give them food and shelter.

Coastal neighborhoods with morning fog and humid summers tend to see more silverfish than drier inland areas, but any house with a leak can have them.

How silverfish control works

1. Inspection of bathrooms, under sinks, closets, garage storage, attic and crawlspace, with attention to leaks and humidity.
2. Identification — silverfish or firebrats — since the hiding places differ.
3. Targeted treatment of cracks, wall voids, baseboards and storage areas using products labeled for silverfish, such as dusts in voids and crack-and-crevice applications. No fogging of living areas.
4. Moisture recommendations — fix leaks, improve ventilation, dry out crawlspaces.
5. Follow-up to confirm activity has dropped; ongoing problems can be folded into recurring service.

Preventing silverfish

• Run the bathroom fan during and after showers; fix fans that don’t vent outside.
• Repair dripping faucets and leaks under sinks, around tubs and at the water heater.
• Use a dehumidifier in damp basements, closets or storage rooms.
• Store papers, photos and seasonal clothes in sealed plastic bins instead of cardboard.
• Reduce stacks of old newspapers, magazines and boxes in garages and closets.
• Caulk gaps along baseboards, around pipes and in bathroom tile.

More background on silverfish and firebrats is available from UC Statewide IPM.

Frequently asked questions