In color it varies from tan to almost black, and it has two dark, roughly parallel, streaks on the pronotum running anteroposteriorly from behind the head to the base of the wings.

[7] The cockroach's sensitivity to cold might reflect its origin from such warm climates, and its spread as a domiciliary pest since ancient times has resulted from incidental human transport and shelter.

The German cockroach occurs widely in human buildings, but is particularly associated with restaurants, food processing facilities, hotels, and institutional establishments such as nursing homes and hospitals.

However, sightings are most frequent in the evening, when someone suddenly brings a light into a room deserted after dark, such as a kitchen where they have been scavenging.

[15] The German cockroach is very successful at establishing an ecological niche in buildings, and is resilient in the face of many pest-control measures.

Conversely, the seasoned pest controller is alert for cracks and crevices where it is likely to be profitable to place baits or spray surfaces.

Though they are not social and practice no organized maternal care, females carry oothecae of 18-50 eggs (average about 32) during incubation until just before hatching, instead of dropping them as most other species of cockroaches do.

Then, after hatching, nymphs largely survive by consuming excretions and molts from adults, thereby establishing their own internal microbial populations and avoiding contact with most insecticidal surface treatments and baits.

[26] The relatively large genome (2.0 Gb) harbours a very high number of proteins, of which most notably one group of chemoreceptors, called the ionotropic receptors, is particularly numerous.

These chemoreceptors possibly allow the German cockroach to detect a broad range of chemical cues from toxins, food, pathogens, and pheromones.