Callosobruchus maculatus is a species of beetle known commonly as the cowpea weevil or cowpea seed beetle. It is a member of the leaf beetle family, Chrysomelidae, and not a true weevil. This common pest of stored legumes has a cosmopolitan distribution, occurring on every continent except Antarctica. The beetle most likely originated in West Africa and moved around the globe with the trade of legumes and other crops. As only a small number of individuals were likely present in legumes carried by people to distant places, the populations that have invaded various parts of the globe have likely gone through multiple bottlenecks. Despite these bottlenecks and the subsequent rounds of inbreeding, these populations persist. This ability to withstand a high degree of inbreeding has likely contributed to this species’ prevalence as a pest.
It is used as a model organism for both research and education due to its quick generation time, sexual dimorphism, and ease of maintenance.