Cockroach, common name for an order of insects, the most familiar of which are characterized by their oval shape, foul odor, and their status as household pests. About 4000 species are known worldwide; most inhabit the warm tropical regions of the globe. About 25 species have attained worldwide distribution due to accidental transport in commerce and their affinity for human habitation. Cockroaches are an ancient group, having changed little in appearance in 320 million years. Cockroaches in general are flat and oval in outline. Cockroaches may be winged or wingless, but even winged species do not always fly. Adults range from 1 mm (0.04 in) to more than 9 cm (3.6 in) in length. They are sensitive to light; most species prefer darkness, being largely nocturnal.
The notoriously disgusting Cockroach provides a versatile source for several chemical-based attacks, and the resilience and speed needed to successfully deliver them. Though weak in direct combat, its abilities to deliver Plague to weak enemies and to set traps for larger enemies by Defiling Land make it a versatile and dangerous unit when properly managed.