Why century-old Unionville homes and brand-new Cornell builds face completely different pest risks — and what to do about each.
Markham is an unusual city to write a single pest control guide for, because it isn’t really one housing type — it’s several. Century-old wood-frame homes in Unionville sit a short drive from brand-new builds in Cornell and Berczy Village on what used to be farmland, and each brings a genuinely different set of pest risks. Knowing which category your home falls into changes what you should actually be watching for.
Heritage Neighbourhoods: Unionville and Markham Village
Older wood-frame construction has had decades to develop the small gaps and softened wood that pests exploit. Homes here tend to see more carpenter ant activity, since older fascia boards, window frames, and deck posts have had more time to take on moisture damage. The same aging foundations and utility penetrations also give mice and rats more of the small openings they need to get inside.
Newer Subdivisions: Cornell, Berczy Village, and Wismer
Homes built on former farmland face a different set of pressures. As landscaping matures — trees growing tall enough to touch rooflines, shrubs filling in — wildlife like raccoons and squirrels gain new access points that weren’t there when the subdivision was first built. Fresh construction can also leave gaps around vents and siding that haven’t been fully sealed, giving mice and insects an opening before a home has had time to settle.
Carpenter Ants: A Citywide Concern in Spring
Wildlife: Squirrels and Raccoons
Grey squirrels in the Markham area typically have two litter seasons — March to April, and again in July to August — and will chew through roof vents, soffits, and fascia to access warm attic spaces during both. This pattern holds across the city, but newer neighbourhoods with maturing tree cover tend to see a noticeable uptick as landscaping fills in.
Mice and Rats
Like the rest of the GTA, activity picks up reliably every September and October as outdoor temperatures drop and mice and rats look for a warmer place to nest for winter. The heritage-vs-new-build split applies here too — older Unionville and Markham Village foundations tend to have more of the small gaps rodents use to get inside, while newer builds are more likely to see an isolated entry point around an unsealed utility line before the home has fully settled.
Wasps and Hornets
Sheds, decks, and eaves are common nesting spots through the summer across Markham, with colonies typically peaking in size by late August. Wasp and hornet nest removal calls tend to cluster in neighbourhoods with larger, more mature yards, like Angus Glen and parts of Unionville, simply because there’s more untouched space for a nest to grow unnoticed.
A Season-by-Season Look at Markham Pest Activity
| Season | What to Watch For |
|---|---|
| Spring | Carpenter ant swarming peaks (May–June); first squirrel litter season begins |
| Summer | Wasp and hornet nests grow quickly; second squirrel litter season (July–August) |
| Fall | Mice and rats move indoors seeking warmth, especially in older-neighbourhood foundations |
| Winter | Rodents and denning wildlife remain the primary indoor concern |
What You Can Handle Yourself
- Sealing visible gaps around utility lines and foundation cracks before fall
- Trimming tree branches back from the roofline as landscaping matures, especially in newer subdivisions
- Checking fascia and window frames for softened wood each spring, particularly on older homes
- Securing garbage and compost bins to reduce wildlife draw
When It’s Worth Calling a Pro
Flying ants indoors in spring, wildlife already inside an attic, or a rodent problem in more than one room are all situations where a licensed technician can identify the species involved and locate both the indoor satellite colony and outdoor parent colony where relevant — not just treat what’s visible.
Quality Affordable Pest Control provides local pest control in Markham with same-day and next-day appointments. We also cover nearby Richmond Hill and Vaughan.
Frequently Asked Questions
Look for a licensed, insured company with experience across Markham’s mix of housing stock, since century-old homes in Unionville face different pest pressure than new builds in Cornell or Berczy Village. Quality Affordable Pest Control offers same-day and next-day appointments across Markham.
Older wood-frame construction develops more small gaps and softened wood over time than newer builds, giving carpenter ants and rodents more entry points and nesting material to work with.
Yes, though the pattern differs. Newer builds on former farmland see more wildlife pressure as landscaping matures, and fresh construction gaps around vents and siding can still let mice and insects inside before homes fully settle.
May and June are peak swarming season in Ontario. Flying ants seen indoors in spring almost always mean an established colony inside the structure, not just an outdoor nest passing through.
Cost depends on the pest, the size of the home, and whether it’s a one-time treatment or ongoing prevention. A free estimate is the most accurate way to get pricing for a specific situation.
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