If you are seeing large droppings near your fence line, finding grease marks along your basement walls, or hearing heavy scratching under your floors at night, you are not dealing with mice. Norway rats are the dominant rat species across Toronto and the GTA, and October is when outdoor colonies start pushing hard toward heated structures. Here is what you need to know about rat control before an outdoor problem becomes an indoor one.
Why Toronto Has a Rat Problem That Is Getting Worse
Toronto’s rodent service requests more than doubled between 2015 and 2024, from 1,165 to 2,523 per year according to city data, and the trend has continued into 2026. Several factors are driving this upward pressure.
Construction activity across North York, Scarborough, and the downtown core continuously displaces established rat colonies into surrounding residential streets. When excavation begins on a major site, the rats living beneath it do not disappear. They migrate outward into adjacent neighbourhoods.
The GTA’s freeze-thaw cycles drive mice and rats indoors from October through March. Lake-effect conditions can push cold air deep into suburban areas, forcing rodents to seek warmth earlier than in sheltered downtown locations.
Toronto’s green bin composting program, while environmentally important, provides an abundant and consistent food source for rat populations when bins are not properly secured. Rats establish territories around reliable food sources and burrow nearby, often under decks, sheds, and foundations within metres of where they are feeding.
Norway Rats vs House Mice: How to Tell the Difference
Most Toronto homeowners cannot immediately tell whether they are dealing with rats or mice. The distinction matters because the control approach, the severity of the problem, and the health risks are all different.
Norway rats are significantly larger than house mice. An adult Norway rat measures 18 to 25cm in body length with a stocky build, blunt snout, small ears relative to its head size, and a thick hairless tail shorter than its combined head and body length. They are brown to grey on top with a paler grey underside.
Norway rat droppings measure 18 to 20mm with blunt ends and are noticeably larger than mouse droppings which are 3 to 6mm with pointed ends. If you can fit a full blueberry in the dropping, it is a rat. If it looks like a grain of rice, it is a mouse.
Rats also leave greasy smear marks along the base of walls, beams, and pipes as they repeatedly travel the same routes. House mice do not leave visible grease trails. Burrow entrances in the soil around your foundation, under your deck, or along your fence line confirm Norway rats.
Signs You Have Rats on Your Toronto Property
Burrow entrances near your foundation or fence line. Smooth round holes 5 to 10cm in diameter with fresh soil mounded around the entrance are Norway rat burrows. They dig tunnel systems up to 60cm deep with multiple chambers and exit points. Finding even one burrow entrance means an established colony is living on or adjacent to your property.
Large droppings near garbage, compost, and garden areas. Rat droppings concentrated near your green bin, compost bin, fence line, and garden beds confirm active foraging on your property every night.
Grease marks along basement walls and pipes. Dark greasy smear marks at the base of your exterior foundation, around pipe penetrations in your basement, and along wooden beams and joists confirm rats are actively traveling through those spaces. These marks build up over weeks of repeated use along the same routes.
Heavy scratching and thumping sounds under floors. Norway rats nest in basements, crawl spaces, and beneath concrete slabs. Their movement is noticeably heavier and louder than mice. If scratching under your floor sounds like something significant is moving around, take it seriously.
Gnaw marks on structural materials. Rats gnaw continuously to control their incisor growth. Finding gnaw marks on wooden beams, floor joists, concrete edges, and lead pipes confirms active rat presence. Fresh gnaw marks are pale and light coloured. Older marks darken over time.
Health Risks of a Rat Infestation
Norway rats carry several diseases that pose direct health risks to Toronto homeowners. Leptospirosis spreads through rat urine contaminating soil and standing water and can cause serious kidney and liver damage in humans. Hantavirus spreads through contact with rat droppings, urine, and saliva and causes Hantavirus Pulmonary Syndrome which carries a significant fatality rate. Salmonellosis spreads through food and surfaces contaminated by rat droppings.
Rats also carry fleas, ticks, and mites that can infest your home and affect your pets. A rat flea problem in a Toronto home is a secondary consequence of an underlying rat infestation that is often not identified immediately.
Why DIY Rat Control Fails
Store bought snap traps and rodenticide bait sold over the counter address individual rats but do nothing to eliminate the colony living under your property. Killing foraging rats temporarily reduces activity but the population rebuilds from the breeding animals remaining in the burrow system beneath your garden or foundation.
Placement matters enormously with rats. Norway rats are neophobic and avoid new objects placed in their environment for days or weeks before investigating. Traps placed incorrectly or in locations rats do not regularly travel will sit untouched while the population continues to grow.
Over-the-counter rodenticides available in Canada are weaker formulations than products available to licensed technicians. They also carry risk to non-target animals including pets, raptors, and wildlife when placed without proper tamper-resistant bait stations.
The most important point: none of these approaches address the burrow system, the entry points into the structure, or the food sources attracting and sustaining the colony. Professional rat control addresses all three simultaneously.
What Professional Rat Control in Toronto Looks Like
A professional rat control program starts with a full exterior and interior inspection to identify all burrow entrances, map travel routes using droppings and grease mark evidence, assess food source attractants, and identify any structural entry points into the building.
Tamper-resistant bait stations are placed directly at burrow entrances and along confirmed travel routes. This is where placement matters. Bait placed where rats actually travel produces results. Bait placed where a homeowner thinks rats might go often sits untouched.
Structural exclusion seals all identified entry points into the building using appropriate materials. Steel mesh, metal flashing, and commercial grade sealants depending on the location. Without this step, new rats move in through the same gaps as soon as the current population is reduced.
Food source reduction addresses the root cause. Green bins secured with proper locking mechanisms, compost management, pet food not left outdoors, and fallen fruit removed from the property all reduce the pressure that sustains a rat colony on your property in the first place.
Our rodent control program includes all of these phases and comes with a written warranty. If rats return within the warranty period, we come back at no charge.
For rat control across North York, Toronto, Scarborough, Vaughan, Markham, Mississauga, and all GTA communities, Saba Pest Control responds 24 hours a day at (647) 867-7378 or sabapc.ca.
How do I know if rats are inside my home or just in my yard?
Grease marks on interior basement walls, droppings on basement floors or in crawl spaces, and scratching sounds coming from under floors or inside walls confirm rats have entered the structure. Burrow entrances and droppings confined to outdoor areas suggest the population is still primarily outside. Either situation warrants professional treatment since outdoor colonies consistently push indoors as temperatures drop through October and November.
Are rats more dangerous than mice?
Yes in several ways. Norway rats are significantly larger and cause more structural damage through gnawing. They carry Leptospirosis and Hantavirus at higher rates than house mice. Their burrow systems cause greater soil displacement around foundations. And their neophobic behaviour makes DIY trapping significantly less effective than it is for the more curious house mouse.
Why do I have rats when my neighbours do not?
Rats establish territories around reliable food sources. An unsecured green bin, accessible compost, a vegetable garden, fruit trees, or outdoor pet food on your property creates the attractant that draws a colony to establish burrows nearby. Construction on an adjacent street can also displace an established colony directly into your yard with no other food source factor involved.
When is the best time to treat for rats in Toronto?
As soon as evidence is found, regardless of season. Fall is the highest-risk period as outdoor populations push toward heated structures, but an active rat colony discovered in any month should be treated promptly. Populations that establish over fall and winter are larger and more entrenched by spring and significantly harder to eliminate.
