Spiders and Centipedes Are Moving Into Ontario Homes This June (2026 Alert)

Quick answer: Ontario’s warm, humid June is pushing spiders and house centipedes indoors, where basements, bathrooms, and laundry rooms stay damp. They are hunting the smaller insects that thrive in summer humidity. Seeing one usually means there is prey — and moisture — to support more. Sani IQ’s general insect control clears them and the conditions behind them.

If you have noticed more spiders in the corners or a fast, many-legged shape darting across the basement floor this month, you are not imagining it. Across the GTA and Simcoe County, the same humid June weather that wakes up mosquitoes and ants is driving spiders and house centipedes deeper into Ontario homes — into the cool, damp rooms we use least and check least often.

This is a seasonal surge, not bad luck. Here is what is happening this month and the calm, decisive way to handle it.

What’s Happening and What to Do

What’s happening	What to do
Humidity is rising, drawing moisture-loving insects indoors	Lower indoor humidity; fix damp basements and leaks
Spiders follow that prey into corners, eaves, and basements	Clear webs; treat entry points and perimeter
House centipedes hunt at night in bathrooms and laundry rooms	Reduce moisture and the small insects they eat
One sighting signals supporting prey and damp conditions	Book a general insect treatment that targets the whole chain

Why Are There So Many Spiders in My House Right Now?

Spiders follow their food. As humidity climbs in June, the small insects spiders eat — gnats, flies, ants, silverfish — multiply and move indoors, and the spiders come with them. As Toronto pest specialists note, the city’s humid summers create ideal conditions for moisture-seeking pests to enter homes, and spiders and centipedes follow that prey inside.

A spider in the corner is rarely the real story. It is a sign the home is supplying insects to hunt. Clearing the spider without addressing what it was eating just leaves the vacancy for the next one.

Are House Centipedes Dangerous?

House centipedes are not dangerous to people — they very rarely bite, and they are not aggressive. They are unsettling because of their speed and many legs, but the bigger signal is what their presence tells you: a centipede indoors means dampness and a steady supply of smaller insects to eat. They are a symptom of conditions, not just a pest.

For a home where zero pest activity is the standard, that is the point. One centipede is a moisture-and-prey indicator worth acting on, the same way one mouse is the start of a problem rather than a one-off.

Can I Get Rid of Spiders and Centipedes Myself?

You can knock down what you see, but the honest trade is time and recurrence. DIY means regularly clearing webs, vacuuming corners, running a dehumidifier, sealing gaps, and chasing the underlying insect supply — week after week, because the prey and the moisture keep coming back through summer. It is real work with an open-ended end date.

A professional general insect treatment is the time-respecting alternative: it dewebs, treats the perimeter and entry points, and targets the insects spiders and centipedes feed on, so the whole chain drops at once. Let the value of your time decide. Sani IQ’s General Insect Control starts at $395 for an exterior treatment or $475 for interior and exterior, and includes dewebbing — see the plans and pricing page.

This Is an Ontario Summer Pattern

In 2026, the GTA and Simcoe County are heading into the hottest, most humid stretch of the year, and indoor pest activity tracks right along with it. Damp basements, bathrooms, and laundry rooms are the rooms to watch — they hold the moisture spiders and centipedes need. Homeowners in Mississauga and Vaughan see the same pattern every July, which is why getting ahead of it in June is the move.

How to Keep Spiders and Centipedes Out: 5 Steps

Run a dehumidifier in the basement; aim for indoor humidity below 50%.
Fix leaks, dripping taps, and damp spots — moisture is the main draw.
Seal gaps around windows, vents, the foundation, and where pipes enter.
Clear webs and clutter in corners, garages, and storage rooms regularly.
Reduce outdoor lighting near doors, which pulls in the insects spiders hunt.

Why Sani IQ

Sani IQ is a licensed, science-based Ontario pest control company. We use integrated pest management — inspection, targeted treatment, and prevention — rather than blanket spraying, so we treat the conditions behind a pest, not just the pest you spotted. Locally operated, fully licensed, and trusted with 100+ five-star reviews, we back every visit with our “Pest-Free, OR It’s Free” guarantee. Learn more on our residential pest control page.

The Bottom Line

A spider in the corner or a centipede in the basement this June is a signal, not a sentence — humidity and prey are supporting them, and both can be handled. Clear the chain now, before the summer peak. Book it and forget about it: call (705) 302-1887 or request a quote at our contact page.

Frequently Asked Questions

Why am I suddenly seeing spiders in my house in June? Rising summer humidity drives the small insects spiders eat indoors, and the spiders follow. A sighting usually means the home is supplying prey. Clearing webs helps short-term, but treating the perimeter and the insect supply is what keeps spiders from returning through the season.

Are house centipedes a sign of a bigger problem? Often, yes. Centipedes need dampness and smaller insects to hunt, so finding one indoors points to excess moisture and an existing insect population. They are not dangerous, but they are a useful early warning that conditions in the home favour pests.

Do spiders and centipedes mean my house is dirty? No. They are drawn by moisture and available prey, not mess — a clean but humid basement is ideal for both. Lowering humidity, sealing entry points, and reducing the insects they feed on matters far more than how tidy a room looks.

How does Sani IQ treat spiders and centipedes? With general insect control: dewebbing, a perimeter and entry-point treatment, and targeting the insects they feed on, so the whole food chain drops together. Treatment starts at $395 exterior or $475 interior and exterior, backed by the “Pest-Free, OR It’s Free” guarantee.

When is the best time to treat for summer insects in Ontario? Early — June, before the July and August humidity peak drives indoor activity to its highest. Treating ahead of the surge keeps numbers low all season instead of reacting once spiders, centipedes, and the insects they hunt are already established indoors.