German Cockroach

Blattella germanica

Size12–15 mm

Colony Size100–10,000

Active Season:Active year-round indoors. Populations can explode rapidly in favourable conditions.

Small tan cockroach with two dark stripes on the pronotum. The most common indoor cockroach pest worldwide, thriving in Canadian kitchens and bathrooms.

Anatomy

Anatomical Details

Identification

ColourTan to light brown with two parallel dark stripes behind head

Size12–15 mm

Distinguishing Features

Two distinct dark longitudinal 'racing stripes' (pronotal bands) on the shield behind the head
Wings present and cover abdomen, but rarely flies—prefers to run
Long antennae, nearly body length
Nymphs darker with single tan stripe down back
Females often seen with egg case (ootheca) protruding from abdomen

Biology

Lifecycle

CRITICAL: Unlike other cockroaches, females carry the ootheca (egg capsule) protruding from their abdomen until ~24 hours before hatching. This maternal care protects eggs from dehydration and pest control treatments—making German Cockroaches significantly harder to eliminate than other species. 30-40 eggs per case, 4-8 cases per lifetime. Nymph to adult in 6-12 weeks.

Diet

Omnivorous scavengers: crumbs, grease, starch, soap, toothpaste, glue. Can survive weeks without food.

Nesting

Thigmotactic (love tight spaces)—prefer cracks no thicker than a credit card. Aggregate in warm, humid harbourages near food and water: refrigerator compressor motors, dishwasher insulation, coffee maker bases, stove clocks, and gaps around plumbing under sinks. The warmth and moisture of appliance motors are ideal.

Signs of Infestation

Live cockroaches at night

Turn on kitchen light at night—roaches scatter to hiding spots.

Pepper-like droppings

Small dark specks in drawer corners, on shelves, behind appliances.

Egg cases (oothecae)

Tan, ridged capsules (8mm) found in protected areas.

Musty odour

Large infestations produce distinctive oily smell from aggregation pheromones.

Where They Nest

Behind and under refrigerators
Inside dishwasher and stove motors
Under sinks around plumbing
Inside electrical outlet boxes
Cracks in kitchen cabinets

Common Nesting Sites

Nesting Site Details

Distribution in Canada

Strictly an indoor pest—cannot survive Canadian winters outdoors. Found nationwide in heated buildings. Introduced via grocery bags, used appliances, cardboard boxes, and supply chain deliveries. Does NOT migrate between buildings through outdoor routes; infestations spread through shared walls in multi-unit housing or by hitchhiking on goods.

Regional Prevalence

High

Moderate

Low

Rare/Absent

Active Season

Active year-round indoors. Populations can explode rapidly in favourable conditions.

House Types at Risk

This pest is commonly found in these home types

Condo / Apartment

High Risk

Shared walls and plumbing allow spread between units. Infestations can become building-wide.

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Townhouse

High Risk

Party walls and shared infrastructure enable movement between attached units.

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Bi-Level

Moderate Risk

Kitchen appliances and bathroom fixtures provide ideal warm, humid harbourage near food.

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Prevention

Clean up food debris immediately, especially grease
Store food in sealed containers
Fix plumbing leaks promptly
Seal cracks around pipes and outlets
Inspect groceries and boxes before bringing indoors

Professional Treatment

Gel baits are primary treatment—placed in cracks where cockroaches harbour. IGR (insect growth regulators) prevent reproduction. Multi-visit programs needed for heavy infestations.

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Insight Pest Canada does not currently treat cockroaches.

Scientific Classification

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Blattodea
Family: Ectobiidae
Genus: Blattella