Overview
The German cockroach (Blattella germanica) is the dominant cockroach species in Montreal apartments and commercial kitchens. Unlike outdoor cockroach species, it lives exclusively indoors and is perfectly adapted to apartment building environments. It is the most difficult household pest to eliminate completely, due to its rapid reproduction, insecticide resistance, and ability to spread through shared building infrastructure.
How to Identify German Cockroaches
- Size: 12–15 mm (adults); 1.5–3 mm (first instar nymphs)
- Colour: Light brown to tan with two distinctive parallel dark stripes running lengthwise down the pronotum (the shield behind the head)
- Wings: Present but rarely used for flight — German cockroaches almost never fly
- Antennae: Long, thread-like, constantly moving
- Speed: Extremely fast — can run 1.5 metres per second
- Activity: Primarily nocturnal; daytime sightings indicate a large, overcrowded population
- Egg cases (oothecae): Brown, purse-shaped, 6–9 mm long, containing 30–48 eggs
Biology & Reproduction
- Oothecae per female lifetime: 4–8
- Eggs per ootheca: 30–48
- Incubation period: 28–30 days
- Time from hatching to sexual maturity: 36–60 days
- Adult lifespan: 100–200 days
- Preferred environment: Warm (25–33°C), humid, with access to food and water
- Harborage behaviour: Thigmotactic — prefer tight contact with surfaces on multiple sides simultaneously
- Aggregation pheromones: Feces contain pheromones that attract other cockroaches to the same harborage areas
Health Risks
- Allergens: Cockroach droppings, shed skins, and saliva are potent allergens linked to asthma development and exacerbation, particularly in children
- Food contamination: Cockroaches spread bacteria including Salmonella, E. coli, and Listeria across food preparation surfaces
- Disease transmission: Documented as mechanical vectors for over 30 species of bacteria and 7 human pathogens
- Psychological impact: Living with an infestation causes significant stress, anxiety, and sleep disturbance
Signs of Infestation
- Droppings: Small (1–2 mm), dark brown to black, cylindrical with blunt ends — resembling ground pepper or coffee grounds
- Egg cases (oothecae): Brown, purse-shaped capsules glued to surfaces in dark, warm areas
- Shed skins (exuviae): Translucent hollow casings in harborage areas
- Musty odour: Distinctive musty, oily smell in heavily infested areas
- Live insects: Seeing cockroaches during the day indicates a severe, overcrowded infestation
- Where to look: Inside cabinet hinges, under appliances, refrigerator motor housing, under the dishwasher, inside electrical outlets
Prevention
- Store all food in airtight containers — cockroaches detect food through cardboard and thin plastic
- Clean kitchen counters thoroughly after every meal preparation
- Take out garbage daily and keep bins sealed with tight-fitting lids
- Fix leaky faucets and pipes — cockroaches need water and congregate near moisture sources
- Eliminate cardboard boxes from the kitchen — use plastic bins instead
- Seal gaps around pipe penetrations under the sink with caulk or expanding foam
- Inspect grocery bags and cardboard boxes before bringing them into the kitchen
- Inspect second-hand appliances thoroughly before bringing them home
Professional Treatment
Professional cockroach treatment uses gel bait as the primary method — applied in 20–40 precise locations where cockroaches travel and harbour. Insect growth regulators (IGRs) are used alongside gel bait to disrupt the reproductive cycle. Treatment typically requires 2–3 visits spaced 2–3 weeks apart. Do NOT use aerosol sprays before or after gel bait treatment — they scatter cockroaches and reduce bait effectiveness.