Rat Control in Scarborough

Dealing with rats in Scarborough means working the outside of the property, not just the inside. Norway rats nest in ground burrows, come up under decks and along foundations, and roam between lots, so a treatment that stops at the kitchen never holds. A real job locates the burrows, seals the openings a rat can push through, and only then sets bait in locked stations. Most Scarborough rat jobs run $300 to $600 or more, take a first visit plus follow-ups, and carry our two-month guarantee. If you are finding droppings the size of a raisin, holes in the yard, or grease-blackened runs along the fence, you have rats, and they rarely turn up one at a time.

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The signs it is rats, not mice

Tell rats from mice by the droppings first: a rat leaves waste about three times the size of a mouse's, roughly the length of a raisin, with blunt rounded ends rather than the small pointed grains a mouse leaves. That one difference tells you which animal you are dealing with and which plan you need.

• Droppings the size of a raisin, dark, capsule-shaped with blunt ends, usually clustered near a food source, along a wall, or by a burrow entrance.
• Burrows in the yard: smooth holes two to four inches across, often against the foundation, under a deck or shed, beside a garbage bin, or into a compost pile, with a fan of loose dirt at the opening.
• Runs and grease marks along fences, foundations, and the base of walls, darker and wider than a mouse leaves because a rat's body is bigger and follows the same path nightly.
• Gnawing on wood, plastic bins, weep holes, and door corners, with shavings underneath. A rat can widen a small gap into an entry in a night.
• Sound in walls, ceilings, or under the deck at dusk, heavier than the light scurrying of a mouse.

If the droppings are small and pointed, read the mouse control page instead, because the treatment is different. Mice are an indoor entry problem. Rats are a yard-and-neighbourhood problem that happens to come inside.

Norway rats are the Scarborough rat

Practically every rat you will find in Scarborough is a Norway rat, also called the brown or sewer rat. It burrows rather than climbs, favours the ground floor and the basement, and nests outdoors through the warm months before pushing inside as the weather turns. That behaviour is why the burrow, not the snap trap, is the centre of the job. A Norway rat will dig a burrow system three feet long with a main entrance and a bolt-hole escape, and it will keep using it as long as there is food and cover nearby.

Kill the rats inside and leave the burrows in the yard, and you have cleared a shift, not a colony. The next set moves in through the same holes within weeks.

Why rats are an exterior problem here

Rats in Scarborough go where the food, water, and cover are, and this part of the city offers all three. The ravine system, Highland Creek and the Rouge in particular, gives rats year-round harbourage, and the lots backing onto those ravines and parks put homes right at the edge of it. Garbage and green-bin organics, backyard compost, and dropped fruit feed them. Construction and sewer work turn over soil and break open old colonies, pushing rats out into the surrounding blocks to find a new home. The City's own Rat Response Plan, which applies here because Scarborough is part of Toronto, names construction disturbance and organic waste among the drivers behind rising rat activity across the city.

That is why we start outside. We walk the property line, the foundation, the deck, the shed, and the garbage area, and we find where the rats are living before deciding where anything goes. Bait in the kitchen does nothing about a burrow under the back deck or on the ravine slope behind the fence.

Why bait alone fails

Bait has its place, but used on its own it is the slowest and least reliable way to clear rats, and around a home it carries real risk. Health Canada requires rodenticides near homes to be used inside tamper-resistant stations, locked boxes a rat can enter but a pet or child cannot, precisely because loose bait poisons the wrong animals. See the PMRA guidance on rodenticide safety.

Three problems with a bait-only approach:

1. It does not close the door. New rats keep arriving through the same burrows and gaps, so the station empties forever and the problem never ends.
2. It can kill a rat in your wall. A poisoned rat dies wherever it happens to be, and a decomposing rat in a wall cavity smells for a week or more with no way to reach it.
3. It moves up the food chain. A poisoned rat that staggers into the open can be eaten by a cat, a dog, or a hawk, which is part of why the City is moving toward reduced-rodenticide, integrated methods.

The bait supports the work. It does not replace it.

Exclusion is the part that lasts

Exclusion is the sealing work that stops the rats you remove from being replaced by the next ones. A rat can squeeze through a gap about the size of a quarter, roughly 20 millimetres, and will gnaw a smaller one wider. So the sealing has to be done in materials a rat cannot chew: galvanized hardware cloth, sheet metal, mortar, and concrete, not foam or steel wool alone, which a determined rat defeats.

The usual entry points we close on a Scarborough property: gaps where pipes and utilities enter the foundation, deteriorated mortar and foundation cracks, uncapped drain and vent openings, gaps under garage doors, and holes gnawed at door and frame corners. Outside, we collapse and backfill active burrows once the colony is controlled, so the harbourage is gone for good.

The neighbourhood dimension

Rats pay no attention to a property line. A colony in a neighbour's woodpile, an unmanaged compost two doors down, or a construction site at the end of the street will keep sending rats onto your lot no matter how tidy your own yard is. That is the frustrating part of a rat problem and the reason it is partly a shared, civic issue rather than a private one. In the ravine-backed pockets of Scarborough this is especially true, because the ravine feeds the whole block.

You can control your own property, which you are required to do, and you can report the wider source so the City can act on it. We cover what to control and what to report in detail on the Scarborough rat problem page, including how and when to call 311. On the ground, the practical move is to strip the food and cover on your side while the whole block does the same, because a single sealed yard beside ten open ones is a much harder win.

Your legal duty to keep the property rodent-free

In Scarborough you are not merely allowed to deal with rats, you are required to. Because it is part of the City of Toronto, the same property standards and rodent rules apply, putting the responsibility on the property owner to keep the property free of rodents and to clear the conditions that harbour them. An owner who ignores a rat problem can face an order and enforcement, not just an infestation.

Common questions

Reviewed August 2026.

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