See also Asp on Wikipedia, and the disclaimer.

Asp, a name loosely applied to several kinds of venomous serpents. A kind of viper in southern Europe and a snake in India, closely allied to the cobra, have received this name. Several kinds of vipers are found in Palestine, and it is not certainly known to which one the word asp in the Bible refers. Cleopatra's famous asp, by means of which she committed suicide, is believed to have been a snake called the homed viper.