German Cockroach

Blattella germanica

The nocturnal lodger in the kitchen crack

The German cockroach is the most common roach indoors: a flat, tea-brown body no bigger than a fingernail, with two dark stripes on the pronotum as its ID mark. It hides by day, roams by night, squeezes through astonishing gaps, and probes the dark with antennae longer than its body.

Key figures

Length

Body 12–15 mm — the smallest of the common indoor cockroaches

Lifespan

Adults live 100–200 days, breeding year-round in heated buildings

Habitat

Kitchens and pipe crevices; favors warm, damp darkness

Diet

Omnivorous — anything from food scraps to paper and wallpaper paste

Running

Covers over 20 body lengths per second, cornering along walls at full speed

Breeding

The female carries her egg case at her tail until just before hatching — 30–40 eggs per case

Life cycle

Egg (in egg case) → Nymph → Adult

Ecological role

In the wild, the cockroach family decomposes leaf litter, but the German cockroach has moved indoors for good, living on crumbs and garbage. Feeding and defecating as it goes, it contaminates food and spreads enteric bacteria, and its molts and secretions rank among the major indoor allergens.

Did you know

The German cockroach isn't German — its homeland was likely Southeast Asia, and it sailed into the world's kitchens with trade. It has nearly lost the wild: without heated buildings, it cannot survive winter.

Range

Worldwide alongside humans; indoors in every season

Status

Extremely common; the number-one indoor cockroach

Anatomy

• Pronotal Stripes — Two parallel dark stripes on the pronotum — the field mark of the German cockroach
• Head — Mostly hidden beneath the pronotum shield; from above only the crown peeks out
• Filiform Antennae — Ever-waving antennae longer than the body navigate the dark by touch and smell
• Forewing — Leathery forewings cover the whole abdomen, yet this fully winged insect almost never flies
• Cercus — A pair of jointed tail bristles senses air currents from behind — an early-warning radar for ambushes
• Spiny Legs — Legs bristling with stiff spines for grip and defense — the engine of its sprint

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