It often starts on a Saturday morning in May. A thin line of small dark ants runs from the gap behind the kitchen backsplash to a smear of jam someone left by the toaster, and by the time you’ve found the spray under the sink there are a few dozen of them.
You wipe them up, spray the corner and the counter is clear by lunch. On Sunday morning the line is back, a little thicker, coming out of the same spot behind the backsplash, and that’s usually when it sinks in that the ants on the counter are only the ones out running errands for a colony living somewhere in the wall, under the patio stones or inside an old stump at the back of the yard.
Somewhere around the second can of Raid, people start googling pest control. Fair enough. Before anybody comes out, though, it’s worth knowing what that colony behind the backsplash is actually doing, because the fix runs almost opposite to what your instincts say.
How a colony works
Numbers first, because they’re a bit ridiculous. A mature colony might hold a few thousand workers, and some species run into six figures. Only a slice of them are out foraging on any given afternoon. The one that found your toast crumb on Friday night walked home laying down a chemical trail, the next few followed it and laid more, and by Saturday breakfast there’s a queue.
And if you were hoping to just get the queen, odorous house ants and pavement ants don’t make that easy, because their colonies often run several queens at the same time.
Why the spray made it worse
Spray kills the ants it touches and not much more. Back in the nest nobody notices. Eggs keep coming, and within a few days there are fresh foragers on the counter. With odorous house ants and pharaoh ants it can get worse still, because stressing them with a chemical can make part of the colony pack up and start over somewhere else, a habit pest people call budding. You began the weekend with one nest behind the backsplash, and by Wednesday there might be another under the dishwasher and a third in the bathroom wall.
There’s a second problem. The ants you just sprayed were the only couriers who could have taken poison back to her. Technicians end up giving advice that sounds a bit mad because of it: don’t wipe the trail, don’t spray it, let them march.
Which ant is it?
Identifying the ant first saves a lot of wasted effort, since what works on one kind can do nothing at all to another. These four are the ones most homeowners around the GTA run into.
| Ant | Size and colour | Usual nest | Telltale sign |
|---|---|---|---|
| Pavement ant | 3 to 4 mm, dark brown to black | Under slabs and patio stones | Small sand piles in driveway cracks |
| Odorous house ant | About 3 mm, brown to black | Walls, soil, under floors | Smells like rotten coconut when crushed |
| Carpenter ant | 6 to 13 mm, black or red and black | Damp or rotting wood | Coarse sawdust, rustling in walls |
| Pharaoh ant | About 2 mm, pale yellow | Warm, heated buildings | Trails that return near sinks and tubs |
If you’re not sure, press a strip of clear packing tape onto a few of them and keep it for the technician, who can also tell you in about two seconds whether a winged one is an ant or a termite.
How bait does the job
Ant bait is meant to be slow, so slow that people often decide it isn’t doing anything, but the ants that eat it go home and pass it along to the larvae and the queen before it kicks in.
Ant appetites shift with the season and with whatever the colony is raising, so one month they’ll mob a sugary gel and a few weeks later walk right past it for something greasy. If yours are ignoring the bait, swap types. Put it right up against the trail, not 30 cm away in a tidier spot, wipe up the jam and juice rings so it’s the best meal on offer, and don’t be alarmed when the line gets busier for a couple of days. More traffic means they’re recruiting to it.
If there’s a toddler in the house, or a dog that eats anything, use the closed plastic stations, the kind nobody can get the bait out of, and slide them behind the stove or into the back of a cabinet. Then, and this is the hard part, leave the whole thing alone for one to two weeks. Grabbing the spray because the line looks worse on day three is how most bait treatments get wrecked.
Carpenter ants
Carpenter ants are the ones that can damage the house. They don’t eat the wood, oddly enough. They excavate it, chewing out smooth galleries to live in, and they go for wood that’s already gone soft from moisture: a window sill where the caulk let go years ago, the rim joist behind a dripping outside tap, porch posts sitting in wet soil.
Frass is what gives them away, and you’d probably sweep it up without a second thought if you didn’t know, since it just looks like a little heap of sawdust under a pinhole in a door frame or baseboard (look closer and there are often bits of ant in it). Some people also say they’ve heard a faint rustling inside the wall at night.
A few big black ants wandering the kitchen in April deserve a note on the calendar. Winged ones crawling out of a wall indoors in February deserve a phone call, since swarmers inside in late winter generally mean a mature colony is living in the house itself. Plenty of carpenter ant colonies also keep the main nest outdoors, in a stump or a dead tree or the bottom of the woodpile, and run smaller satellite nests indoors. Knock out the indoor one only and the outdoor one simply restaffs it.
Ants trekking across the bathroom floor in January get the same treatment. In July they could be strolling in from the garden. With snow on the ground, the colony is almost certainly inside somewhere warm, beside the furnace flue maybe, or along a hot water line.
Why they keep coming back
- The old trail, if nobody wiped it down with soapy water afterwards.
- Tiny gaps around window frames and baseboards.
- Something damp, like a leak under the sink.
- Aphids on a shrub out front, which ants look after for the honeydew.
- A shared wall with the neighbours in a semi or townhouse.
What home remedies can and can’t do
Vinegar and soapy water are handy for wiping out the scent trail once the bait has done its work. Peppermint oil and cinnamon get a lot of love online, and they’ll move ants off a particular windowsill for a bit, after which the ants simply go round. Diatomaceous earth does kill ants that crawl through it, but the queen never crawls through anything, so it ends up as one more way of killing foragers.
Check the yard as well
I’d also have a look outside, since plenty of the ants in a kitchen are walking in from the yard every morning. Sand between the patio stones, ants going in and out of a weep hole in the brick, or a busy shrub near the door are all worth noticing, and if you have old landscape timbers or a stump, push a screwdriver into it and see if it’s soft. Pulling the mulch back from the foundation and cutting the shrubs off the siding helps more than most of what’s sold in the bug aisle.
Want to have a go yourself before calling anyone? Bait right beside the trail plus a bit of patience will handle a lot of simple cases, and the caulking and leak-fixing can wait until the ants have gone quiet, otherwise you just push the trail into another room.
Calling someone in
Two weeks of bait and no change is the point where I’d stop. Same goes if they’ve spread into other rooms, if you’ve seen frass or winged ants inside, or if you still can’t tell where the trail starts, and at that stage a technician can name the species, follow the trail back home and use something the colony will actually carry in.
Brampton has subdivisions built in the last twenty years sitting right next to streets of older Bramalea-era bungalows, and the ant problems in each tend to be different. If you’re comparing companies for pest control in Brampton, ask whether they’ll look for moisture and entry points as well as treating the ants, since that’s usually what stops the return visits.
Most ant problems that drag on for months turn out to be a damp spot or a gap nobody found, with the ants just the part you can see.
