Silverfish Control in York Region

Silverfish are the small, silver-grey, teardrop-shaped insects that shoot out from behind books and baseboards when a light comes on, and in York Region they almost always trace back to one thing: a humid finished basement. They do not bite, sting, or carry disease, but they feed on the starch and cellulose in paper, cardboard, book bindings, wallpaper paste, and natural fabrics, so a real infestation quietly chews through the boxes and documents you have stored downstairs. The fix is not a spray you repeat forever. Silverfish live where it is damp, and until the lower level dries out they keep coming back. We treat the harbourage and tell you which humidity or leak problem is feeding them. The same damp basement draws house spiders, so silverfish often arrive with a spider control problem, and typical prices for both are on our pest control cost York Region guide. Free inspection, same-day service, two-month guarantee.

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How to tell if you have silverfish

The clearest sign is the insect itself: 12 to 19 millimetres long, silver or grey, carrot-shaped and tapering to the tail, with three bristles at the back and two long antennae, moving in a fast wriggling dash. You usually spot them at night in a basement bathroom or a storage room when the light goes on. When you are not seeing the bug, look for the traces they leave behind:

• Pepper-like droppings, dark specks that look like coarse ground pepper, on shelves, in drawers, and inside stored boxes.
• Yellowish stains and small holes on paper, book pages, wallpaper, and stored clothing, with the surface layer usually scraped away rather than eaten straight through.
• Shed skins, thin translucent moults near feeding sites, because silverfish keep moulting their whole lives.
• Grazed edges on cardboard boxes and book spines where they feed on the starch in the glue and paste.

Silverfish are a symptom of a moisture problem. The insect is what you notice; the damp is what is actually wrong. If you are finding droppings and yellow stains in a finished-basement closet or a storage room, whatever is in there has been feeding them for a while.

Where silverfish hide in York Region homes

Silverfish want the dampest, darkest, most paper-rich corners of a house, and the way York Region homes are built hands them exactly that. The pattern splits two ways:

• Finished basements in the newer detached homes of Markham, Vaughan, and Richmond Hill. The large 1990s-to-2010s subdivision builds almost all have a finished lower level, and a finished basement that is not ventilated the way the main floors are traps humidity against drywall, carpet, and stored boxes. That is prime silverfish habitat.
• Utility and storage rooms around the furnace, the water heater, the laundry, and the sump, where warm damp air collects and cardboard sits on a concrete floor.
• Bathrooms, especially the basement or lower-level bathroom, behind the toilet, under the vanity, and in the gap behind wall tile wherever a fan is missing or unused.
• Older homes in the historic cores of Aurora, Newmarket, Unionville, Markham Village, and Thornhill, where older foundations, plaster, and decades of stored paper hold damp the way newer construction does not.
• Book and paper storage anywhere in the house: bookshelves, filing boxes, and archived documents are a food source and a hiding place at once, and the larger York homes tend to store a lot of it.

The common thread is not the age of the home, it is trapped humidity plus stored paper. A new Vaughan build with a finished basement can have the same problem as a century home in downtown Newmarket.

The honest fix: dry the lower level out first

The one thing that ends a silverfish infestation is taking away the moisture they depend on. Silverfish need high humidity to survive and breed, so drop the relative humidity and they cannot hold on no matter what gets sprayed. Before or alongside any treatment, this is what does the real work:

1. Run a dehumidifier in the finished basement, the utility room, and any damp storage area, holding relative humidity below about 50 percent. In a York Region basement this one step breaks most infestations over a few weeks.
2. Fix the leaks. A dripping trap under a vanity, a slow toilet, a weeping foundation corner, or a laundry connection. Silverfish cluster wherever the water is.
3. Ventilate. Use the bathroom exhaust fan during and after showers, and make sure a finished basement gets real airflow rather than sitting sealed and stagnant.
4. Cut the food and shelter. Move stored paper, books, and cardboard off the basement floor into sealed plastic bins, keep pantry goods in sealed containers, and vacuum shelf edges and cracks to lift eggs and droppings.

How Insectica treats silverfish

We pair targeted product with the moisture guidance above, because product without the moisture fix is only a temporary result. On a silverfish job we:

• Inspect for free to map where they are feeding and, more to the point, where the damp is coming from.
• Apply crack-and-crevice treatment with Health Canada PMRA-registered product placed directly into the harbourage: baseboard gaps, cracks around tile and plumbing, the backs of shelves and cabinets, and wall voids.
• Hand you the moisture plan specific to your home: which room to dehumidify, which leak to fix, which storage to move, so the result actually holds.

Every product we use is PMRA-registered and applied to the label. The work is carried out by Insectica Pest Control, owner-operated and not a franchise, and there is no upsell: if the honest fix is a dehumidifier in the basement and a repaired trap under the vanity, that is what we will tell you.

The other pests that follow the same damp

Silverfish share their humid, hidden habitat with the other moisture-loving pests, so finding one often means the conditions are right for others. If you are also seeing something faster and larger in the basement or kitchen at night, read the cockroach control page, because roaches want the same warm, damp cracks. Ants also push indoors following moisture; the ant control page covers those. For what any of this runs, the pest control cost page breaks it down by pest and home size.

By town: silverfish in Markham, Richmond Hill, Vaughan, Newmarket and Aurora

Silverfish follow damp, so the question in every town is how the lower level was built and how dry it stays.

• Markham: older homes in Unionville and Markham Village with original basements, and finished basements with below-grade bathrooms across the subdivisions.
• Richmond Hill: homes near Lake Wilcox and the Moraine with higher groundwater, and finished basements in Jefferson and Richvale.
• Vaughan: large finished basements in Woodbridge, Maple and Vellore, where a basement bathroom or laundry keeps humidity up.
• Newmarket: the older homes near Main Street and Fairy Lake, with older foundations that wick moisture.
• Aurora: heritage homes in the Yonge and Wellington core, and finished basements in Regency Acres and Aurora Highlands.

Common questions

Reviewed October 2026.

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