Too many spiders in the house: where they come from and how to keep them in check

Spiders and crawling insects are among the most common pests in Greater Montreal homes. From Montreal to Laval and the South Shore, it's the same story: you clear away the webs, and they come back. Here's why, and what to do about it.

Spiders follow their food

A spider comes into a building for one simple reason: to eat. Wherever flies, gnats, ants or other small insects go, spiders move in. So a lot of spiders almost always points to another insect problem. Until that's dealt with, the webs will keep coming back.

The most common spiders around here

• House spiders, very common in corners and on ceilings, and harmless.
• Cellar spiders, with long, thin legs, found in basements and garages.
• Garden spiders, mostly found outdoors, which cover exterior walls and soffits with webs in late summer.

What attracts them

• Outdoor lighting, which draws insects to doors and windows.
• Quiet, dark spots: basements, garages, under decks, eaves.
• Easy ways in: cracks, damaged screens, poorly fitted doors, ducts.
• The change of seasons, which sends spiders looking for shelter in the fall.

How to keep them in check long-term

• Cut back on outdoor lighting you don't need, or choose bulbs that attract fewer insects.
• Seal cracks and repair screens.
• Keep the basement and garage clutter-free, clean and well ventilated.
• Remove webs and egg sacs regularly.
• Have the exterior treated early in the season: the barrier means fewer insects on your walls, and fewer spiders along with them.

If spiders keep coming back despite all this, a professional treatment goes after the spiders, the insects they feed on and the ways in, all at once. That's what makes the results last.