Boidae is a family of the New World tropics and subtropics, with most species in Central and South America. Two exceptions live in the western United States, and both are small, secretive and slow.
Lichanura trivirgata is a stocky boa under a metre long, striped lengthwise in rose, brown or grey, that shelters among boulders in desert canyons and emerges at dusk to hunt woodrats, mice and young rabbits. It kills by constriction like its tropical relatives, and like them bears live young rather than laying eggs. The rubber boa, Charina bottae, is the northern counterpart, a blunt, smooth, plain-brown snake that reaches southern British Columbia and is among the most cold-tolerant boas in the world.
Both species are docile and rely on retreat rather than defence. The rubber boa presents its blunt tail as a decoy head when threatened, taking bites there rather than on the real one; older individuals often carry a scarred tail as evidence. Rosy boas are slow enough that collection for the pet trade has been a genuine local pressure, and several jurisdictions restrict it.