Lachesis, also known as bushmasters, is a genus of venomous pit vipers found in forested areas of Central and South America. The generic name refers to one of the Three Fates, Lachesis, in Greek mythology who determined the length of the thread of life. Four species are currently recognized. Adults vary in length from 2 to 3 m (6.6 to 9.8 ft), although some may grow to as much as 4 m (13 ft), making it the longest venomous snake in the Western Hemisphere. Bushmasters are the longest type of viper in the world. L. muta is possibly the largest of the three species currently recognized, although more scant information suggest L. stenophrys broadly overlaps in size and may average at a similar size, while L. melanocephala and L. acrochorda are seemingly slightly smaller than the prior two species. Although they are not the heaviest vipers, being surpassed in mass by the Gaboon viper and the Eastern diamondback rattlesnake, large adults still can weigh up to 3 to 7 kg (6.6 to 15.4 lb). Bushmasters are sexually dimorphic in size, with males reaching larger sizes than females. The bushmaster's tail ends with a horny spine which sometimes vibrates when disturbed like rattlesnakes. This has led to some calling it 'the mute rattlesnake'. (Source: Wikipedia.org, CC BY-SA)