Fer-de-lances are the most feared snakes in Costa Rica, even if they are not the largest species to be found here. They have grown a reputation out of casual encounters and deadly accidents. Part of the reason is that Fer-de-lances are more frequently found close to human settlements than other vipers, creating more chances to see them close. They normally do not display aggressiveness towards humans, preffering to stay concealed and motionless, however this very behavior make them hard to detect. It is common for people working on the field to tell stories of snakes passing through their legs; if not for that, they would have gone unnoticed. When a human is close, their usual reaction is to leave, but sometimes if they feel threatened, they will launch an attack, with potentially devastating consequences for the victim.