Ontario’s Spring Ant Surge: What You Need to Know

By Mike Pearson  |  InsideHalton.com

Warmer temperatures and spring rains are driving ants out of winter dormancy and into Ontario homes. While most are a minor nuisance, some species pose a serious structural threat. Jeff Bow, branch manager at Abell Pest Control (Ottawa), offers expert guidance.

Know Your Ants

• Carpenter ants — The top pest call for Abell. Large, mostly black. Don’t eat wood like termites, but hollow it out. Thrive in water-damaged wood and foam insulation. Can damage sill plates and structural beams.
• Pavement ants — A nuisance species. Found around patios and home exteriors; enter basements through tiny foundation cracks. Can displace soil under interlocking stone and driveways.
• Pharaoh ants — Also a nuisance species; less common.

Warning Signs

• Piles of sawdust (often mixed with ant exoskeletons) — indicator of carpenter ants
• Foundation or exterior cracks, especially near doors, windows, pipes, and utility lines
• Ant mounds in soil near the home foundation
• Moisture intrusion through skylights or around gutters — ants will exploit it

Prevention: Keep Ants Out

• Trim tree branches touching walls or roof (they act as ant highways)
• Store firewood well away from the home
• Seal all exterior cracks, gaps, and entry points with caulk
• Fix leaky pipes, gutters, and AC units to eliminate moisture buildup
• Keep compost bins away from exterior walls; clean up food and beverage spills promptly
• Store sugary or greasy foods (e.g. peanut butter) in sealed glass jars
• Place pet food dishes in a shallow dish of water to block ant access

Control Methods

DIY options:

• Flood nests repeatedly with a garden hose or pour boiling water and detergent down them
• Place two-sided tape around plant stands — ants won’t cross sticky barriers
• Diatomaceous earth — a natural powder that dehydrates ants; safe for humans and pets (don’t inhale); apply in cracks and crevices
• Gel insecticides — laced sugar/protein bait carried back to the colony; only effective if the queen also consumes it

Important: Always look for a Health Canada PCP number on any pest control product. Avoid ordering products online from outside Canada. A colony can exceed one million ants — DIY may not be enough.

Bow recommends consulting a licensed pest control professional to identify the species and determine an integrated pest management approach.