Every spring, London, Ontario homeowners start noticing trails of ants across countertops, along window sills, and near entry doors. This isn't random — ant activity follows temperature and moisture patterns, and late April through June is the peak window for forager ants entering homes in Southwestern Ontario.
The Species That Actually Matter
Not all ants are the same problem, and misidentifying them leads to wrong treatments.
Pavement Ants
Small (2–3 mm), dark brown to black. Common around foundations, patios, and in gaps between concrete. They forage indoors for sweets and proteins. Manageable with perimeter bait programs.
Carpenter Ants
Larger (6–13 mm), black or red-black. These do not eat wood — they excavate it to build galleries. Finding frass (sawdust-like material) near wood is a sign of an active satellite colony in your structure. This warrants professional ant control treatment, as damage can be significant.
Odorous House Ants
Small, dark, and they smell distinctly like rotten coconut when crushed. They forage aggressively and colonies can be large and distributed, making them difficult to eliminate with over-the-counter sprays.
Pharaoh Ants
Tiny (1–2 mm), yellow-orange. More common in multi-unit buildings. Extremely difficult to eradicate without gel bait programs — sprays cause colony fragmentation and worsen the problem.
Why Spring Is the Critical Window
Ant colonies overwinter in deep soil or wood structures. When soil temperatures rise above 10°C, forager ants emerge to establish new food trails and expand territory. Acting early — before the colony fully mobilizes — means a smaller, faster-resolving treatment program.
Common Mistakes That Make Ant Problems Worse
Spraying visible ants with residual insecticides. This kills foragers but doesn't reach the queen. With no foragers returning, the queen senses a threat and splits the colony — a process called "budding" that creates new satellite colonies elsewhere.
Using repellent barriers inside without finding the entry point. You redirect the trail; you don't solve the problem.
Ignoring carpenter ants. A carpenter ant infestation is not just an annoyance — active galleries in structural wood weaken your home over time. Early treatment prevents costly repair.
The Effective Approach
1. Identify the species — treatment strategy differs by ant type
2. Locate the primary nest or entry point — exterior perimeter inspection included
3. Apply appropriate bait or treatment — non-repellent bait for most species; void injection for carpenter ants
4. Follow perimeter exclusion steps — seal gaps, trim vegetation touching the structure
5. Monitor with a follow-up visit or baiting station check
Get an ant inspection booked for your London home — or read more about our ant control service.
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Ant Control