The Western whip snake was first described by Lacepède in 1789, formally Coluber viridiflavus: Coluber meaning fast moving, whipping, hence the name "whip snake". Now known as Hierophis viridiflavus, Hierophis meaning sacred and snakes "sacred snakes". Viridiflavus is made of two words "viridi(s)" meaning green and "flavus" meaning yellow, making their other common name, the Dark green whip snake.
They are characterised by a black body decorated with various yellow freckles and spots sometimes even forming a series of vertical lines on the flanks and forming a striped tail. Juveniles are rather different.
They hatch at around 30 cm, averaging about 100 cm, growing up to 150 cm.
They are strongly built but elegant. They have long tails and a small yet distinguished head.
=Patterns & colours=
Their patterns and colour change throughout their life. Juveniles are born with a dark head with lighter, usually yellow markings. Their body is more grey or greyish brown in colour, with future yellow markings being hard to see, but they are slightly different in colour, sometimes light orange. As they grow older, their body darkens and slowly becomes black. In some parts of its range, the yellow markings are not very obvious. However, in France they can be spectacular. A typical adult is black with many yellow markings on back and flanks.