The Boas (Boinae) are a subfamily of non-venomous snakes. They are found in the wild in South America, Central America, and parts of Africa and Southeast Asia. The boas and pythons are often confused by non herpetologists, and many species of both families are superficially very similar, and share many similar features. The Emerald Tree Boa for example is very similar in appearance to the Green Tree Python, but taxonomically there are several major differences.

Emerald Tree Boa, very similar in appearance to the Green Tree Python

Perhaps the biggest difference between the boas and pythons is that the pythons lay eggs, while boas give birth to live young. There are also distinguishing physical features since the pythons have postfrontal bones or premaxillary teeth which are absent in the boas. Geographically their distributions are almost exclusively distinct.

It’s worth noting that often, especially in older books, pythons are classified as a subfamily of Boidae, the Pythoninae. Almost all modern classifications however have Pythons as a quite separate family. Now the family Boidae consists of the True Boas (Boinae) and the Old World Sand Boas (Erycinae)

Boas are considered a relatvely primative snake and the remnants of hind legs can still be found, especially on males, in the form of anal spurs either side of the cloaca (vent). In general they are medium to large sized snakes, with the males usualy a little smaller than the females.

The name Boa comes from bos, the latin name for cow. It is thought that this is based on an old myth where the boas would kill cows by suckling their blood.