Why Ontario Pest Control Is Now a Year-Round Job

Are Ontario winters getting milder?

Yes: Ontario's mean annual temperature rose 1.3°C between 1948 and 2016, and across Canada winters have generally warmed more than summers. For a long time the pattern in Ontario was simple. Pests built up through spring and summer, then died back over the winter.

Environment and Climate Change Canada says average winter temperatures across Canada have warmed by 3.7°C over the past 78 years. In winter 2023/2024, the Great Lakes/St. Lawrence climate region, which covers southern Ontario, had its warmest winter on record at 5.4°C above its baseline average.

Health Canada says cockroaches are attracted to buildings by the warm, damp conditions of kitchens, bathrooms and basements, and the German cockroach has been found in buildings as far north as Nunavut. Health Canada also says swarms of winged carpenter ants trying to get outdoors usually appear in the spring, and colonies can nest inside wall voids, attic spaces and hollow doors. For rodents, it says mice can squeeze through cracks as small as a dime, while rats can enter through a quarter-sized hole, and deer mice may invade buildings near fields and woodlands in the fall.