Red firebugs, invasive insects from Europe and western Asia, are swarming in Toronto, entering homes in large numbers and causing nuisance due to odor, but they are harmless and do not damage property.

Red firebugs, invasive insects from Europe and western Asia, are increasingly common in Ontario, especially in Toronto, as they gather on little leaf linden trees and seek shelter in homes during cooler weather. First spotted in North America in 2008, they cannot fly, are harmless to humans, and do not spread disease or damage property, but their large numbers and foul odor when disturbed can be a nuisance. They enter homes through small gaps, and their pheromones attract more bugs. Experts recommend sealing entry points, using screens, vacuuming infestations, and managing outdoor populations with soapy water or high-pressure hoses. The City of Toronto advises against squishing them to avoid odors and stains.