The crab-eating macaque (Macaca fascicularis), also known as the long-tailed macaque and referred to as the cynomolgus monkey in laboratories, is a cercopithecine primate native to Southeast Asia. A species of macaque, the crab-eating macaque has a long history alongside humans. The species has been alternately seen as an agricultural pest, a sacred animal, and, more recently, the subject of medical experiments.