Overview
American cockroaches are substantially larger than German cockroaches. Ontario encounters are more often connected with drains, utility areas and large commercial or institutional buildings than with small kitchen harbourage.
A single large cockroach may have moved from a drain or shared service area, but repeated activity requires investigation of moisture, plumbing routes and protected harbourage.
Identification
Adults are large and reddish brown, with long wings and a pale yellowish margin or figure-like marking on the pronotum behind the head.
Their size separates them from German and brown-banded cockroaches. Oriental cockroaches are smaller, darker and have reduced wings.
Life cycle
Females deposit egg cases in protected locations near food and moisture.
Development is slower than in German cockroaches and varies considerably with temperature, humidity and food availability.
Habitat and behaviour
Common harbourage includes sewer and floor-drain systems, boiler rooms, steam tunnels, mechanical rooms, basements and commercial food facilities.
Warmth and persistent moisture are major factors.
Diet
They feed on a wide range of organic material, including food residue, garbage and decaying matter associated with drains or service spaces.
Signs of activity
- Large reddish-brown cockroaches
- Activity near drains or mechanical rooms
- Droppings in protected travel routes
- Egg cases in warm sheltered crevices
- Repeated nighttime activity in basement or food-service areas
Property and health concerns
Cockroaches can move through unsanitary areas and contaminate food or preparation surfaces. Droppings and body material may also affect people with asthma or sensitivities. The following concerns may apply depending on the species and location:
- Transfer of contaminants from drains or waste areas
- Allergen material from droppings and shed skins
- Food-service and commercial sanitation concerns
- Movement through shared plumbing infrastructure
Seasonal activity in Ontario
Heated infrastructure can support activity throughout the year. Outdoor and drain-associated movement can become more noticeable during warm, humid periods.
How they enter buildings
- Floor drains and sewer connections
- Utility penetrations and pipe chases
- Service corridors and mechanical spaces
- Deliveries or materials from an affected facility
Prevention considerations
- Maintain drain covers and plumbing seals
- Repair leaks and condensation
- Keep waste areas clean and closed
- Seal service penetrations
- Monitor basement and mechanical areas
- Inspect incoming materials in high-risk facilities
Never use an unregistered product or apply a product contrary to its label. Do not combine treatments. Contact a licensed professional for recommendations appropriate to your property.
Professional inspection and treatment
Effective control begins with species confirmation, harbourage inspection and an assessment of food, moisture and structural conditions. A professional plan may include:
- Confirm whether activity originates in the occupied room, a drain system or a shared service area.
- Inspect moisture, sanitation and structural routes before selecting treatment.
- Coordinate with property management when infrastructure is shared.
- Follow Health Canada label requirements for any pesticide application.
References
Last reviewed: July 30, 2026. Website information is educational and does not replace an on-site inspection.