Boa Snake - Boa, Name for a member of the Boinae , a subfamily of non poisonous constrictors snakes that includes the anaconda and is closely related to the python. The boa constrictor of South America is rarely over 12 ft. long; those of Central America may reach 15 ft.. Most West Indian boas are valued as rodent killers. Tree bowers are indigenous to tropical America, but 1 species occurs in Madagascar. Burrowing, or sand boas are found in Africa , India, and West North America. The rubber boa is found in the North West United States ; the rosy boa, in the southwest .