The lifespan of a cockroach varies by species.
Adult German cockroaches live about 100–200 days, and development from egg to adult takes about 60 days, meaning an individual German cockroach's total lifespan is roughly 5–8 months.
The American cockroach lives longer, with adults reaching 1–2 years.
But even more critical is their reproductive capacity: a single female German cockroach can produce 4–8 oothecae in her lifetime, each containing 30–40 eggs.
Under ideal conditions, starting from a single pair of German cockroaches, the theoretical number of offspring can reach hundreds of thousands within a year.
The nymph (immature) stage of cockroaches is an easily overlooked aspect in control—nymphs lack wings, are smaller, hide more easily, and may have different sensitivity to certain pesticides compared to adults.
Many DIY control failures happen because only the visible adults are killed, while the nymphs and oothecae hidden deep in cracks are not affected.
Two weeks later, the eggs hatch, and new cockroaches appear.