Cockroaches in St. Louis

Common Cockroaches in the St. Louis Area

Three species cause nearly all local infestations. Here’s how to tell them apart — and why each one matters.

German Cockroach

Blattella germanica

Identify: Small — ½ to ⅝ in., pale to medium brown, with two dark stripes running down the pronotum behind the head. Has wings but never flies.

Life cycle: Females carry the egg capsule until about a day before it hatches; each capsule holds 30–48 eggs, and a female produces 4–8 in her lifetime. Egg to adult in as little as ~40 days when warm — which is how infestations explode.

Habits & risk: Hides close to warmth, food and moisture — kitchens and bathrooms. Hitchhikes indoors in cartons, bags and deliveries. Droppings and cast skins are potent asthma and allergy triggers.

American Cockroach

Periplaneta americana

Identify: The largest common roach — 1½ in. or more, reddish-brown with a pale yellow border around the pronotum. Also called the “water bug” or “palmetto bug.”

Life cycle: The female drops a dark brown egg capsule of 14–16 eggs about once a week — up to 15–90 over her life. Adults can live 15+ months.

Habits & risk: Favors warm, damp, dark places — basements, crawlspaces, floor drains, sewers and steam tunnels. Feeds on decaying matter and tracks bacteria onto surfaces.

Oriental Cockroach

Blatta orientalis

Identify: About 1 to 1¼ in., very dark brown to nearly black with a greasy sheen. Neither sex can fly.

Life cycle: The female carries the capsule about 30 hours, then drops it; roughly 8 capsules of 16 eggs each. Populations follow a season, peaking in late spring and early summer.

Habits & risk: The dampest, coolest “water bug” — drains, basements, crawlspaces, mulch and retaining walls. Sluggish, avoids light, and moves indoors during drought or cold.

Identification and biology per Truman’s Scientific Guide to Pest Management Operations.