In adders of the genus Bitis females have much shorter tails than males but without another tail to compare with it could be confusing. In the Boomslang males are usually green or in the Cape provinces dark blackish above with yellow, green or orange sides whereas females are usually brown in colour. But it could be the other way around and juvenile Boomslang are greyish with big emerald eyes. In some other snakes, males may have longer tails than females but this is certainly not a universal rule.To accurately establish the sex of a snake a metal probe is inserted into the sexual organs towards the tail – in males the probe easily goes down more than 10 subcaudal scales and in females no more than three.

The photograph below illustrates the tail length differences in the Puff Adder.