Identify the species first
| Species | Size | Colour | Habitat | BC home commonality |
|---|---|---|---|---|
| Pavement ant (Tetramorium) | 2-4 mm | Dark brown to black | Kitchen trails, sidewalk cracks | Most common |
| Carpenter ant (Camponotus modoc) | 6-13 mm | Black, sometimes red-and-black | Moist wood inside structures | Structural pest #1 in BC |
| Odorous house ant (Tapinoma sessile) | 2-3 mm | Brown to black | Kitchen, bathroom moisture | Common |
| Thatching ant (Formica spp.) | 5-8 mm | Red and black | Outdoor mound nests | Yards, rarely indoors |
| Pharaoh ant (Monomorium pharaonis) | 1-2 mm | Light yellow-brown | Hospitals, multi-unit buildings | Less common in detached homes |
Why hardware-store perimeter spray fails
Most homeowners' first instinct is to spray perimeter pesticide on visible ant trails or around the foundation. This kills the workers you see — but ant colonies have 90% of their members hidden in the nest. The remaining workers detect the dead ones via pheromones, and the queen responds by laying more eggs and sometimes by 'budding' the colony into multiple satellite nests. You go from one ant trail to three. The right approach is non-repellent product that workers carry into the colony and feed to the queen.
The right protocol
Ant elimination protocol — Metro Vancouver
The protocol every Wild Pest tech follows for confirmed ant infestation, varied by species.
- 1Identify the speciesWatch a single worker for 30 seconds. Size, colour, and trail pattern usually narrow it down. Photograph one for comparison if needed. Refer to the identification table above — getting this right saves you from buying the wrong bait type.
- 2Locate the trail and nestFollow the trail back to its source. Indoor trails usually trace back to an exterior entry — under a baseboard, behind a kitchen cabinet, around plumbing. Outdoor trails trace back to a nest in soil, mulch, or stone. For carpenter ants, look for [frass](/guide/carpenter-ant-frass) — fine wood shavings — below the trail to locate the gallery.
- 3Apply non-repellent gel bait at activity sitesUse a registered ant gel bait at the trail. Workers feed, return to the colony, and feed the queen. The colony declines over 7-14 days. Do not spray near the bait — repellent product breaks the bait pickup.
- 4For carpenter ants: add a moisture auditCarpenter ants follow water. Identify the moisture source feeding the colony — failed flashing, plugged gutter, rotted deck ledger, condensation issue. Treatment without fixing moisture leaves the colony rebuildable. Repair the source within 30 days of treatment.
- 5Monitor for 14-21 daysTrail activity drops to zero typically by day 7-10 for pavement ants, day 14-21 for carpenter ants. If still active past day 21, you missed a satellite colony or there are multiple colonies — re-inspect.
- 6Seal entry points after colony has declinedCaulk baseboards, foam around plumbing penetrations, weatherstrip door bottoms. Sealing before the colony is gone traps workers inside and can cause the colony to split into multiple satellite locations.
BC-specific context: why Metro Vancouver has so many ants
The Pacific Northwest climate is unusually favourable for ants. Metro Vancouver receives over 1,200 mm of precipitation annually, creating the persistent soil moisture that pavement and odorous house ants need. The region's older housing stock — a significant portion of Burnaby, East Vancouver, and Richmond detached homes were built before 1980 — has large gaps in aged weatherproofing, deteriorated cedar siding, and inadequate under-slab drainage that makes carpenter ant establishment straightforward. The result is that BC homes average more ant callbacks per year than the national average.
What the BC IPM Act requires
Under BC's Integrated Pest Management Act (RSBC 1996 Chapter 133), commercial pesticide application requires a valid applicator licence. Homeowners may apply pesticides on their own property using products registered for home use under Health Canada's Pest Control Products Act. This includes most hardware-store gel baits. Professional-grade products (higher-concentration formulations, restricted pesticides) require a licensed applicator. If your situation escalates to the point where professional product is warranted, verify your contractor holds a valid BC Class 5 or Class 7 licence through the Ministry of Environment's online registry.
When to call a pro
- Active carpenter ant activity with frass present — structural damage risk justifies professional inspection and treatment.
- Activity that persists beyond 3 weeks of diligent bait application.
- Pharaoh ants in a multi-unit building — require coordinated treatment; independent DIY efforts can scatter the colony.
- Any ant activity that you cannot trace to a source entry point — the colony may be in an inaccessible void.
- Swarmers (winged ants) indoors in spring — almost always carpenter ants and indicates a mature colony in the structure.