Types of eyelash-vipers

Bothriechis is a genus of venomous snakes in the family Viperidae, the viper family, and within it the pit viper group. Like all pit vipers, its members carry a heat-sensing pit between each eye and nostril that detects warm-blooded prey, paired with long, hinged front fangs that fold against the roof of the mouth and swing forward to strike. What sets Bothriechis apart is its commitment to life in the trees. These are the arboreal palm pit vipers, built long and light with strongly prehensile tails for gripping branches and vines.

The genus is centered on Central America and the northern edge of South America, ranging roughly from southern Mexico through Guatemala, Honduras, Nicaragua, Costa Rica, and Panama into Colombia and parts of the Andes. Many species are tied to wet forest, especially cloud forest and mid to high elevation rainforest, where they spend their lives off the ground among foliage, palm fronds, and mossy limbs. Some are restricted to a single mountain range or isolated highland, which makes several species narrow in range and of conservation concern.

Recognizing a Bothriechis usually means spotting a thin viper coiled in vegetation rather than on the ground. The head is broad and triangular, the neck narrow, the body relatively slim, and the tail clearly grasping. Color is highly variable across and within species, running through greens, browns, yellows, and speckled patterns that blend into leaves and bark. The best known members, the eyelash vipers, add a giveaway feature: raised, bristle-like scales over each eye that look like eyelashes or small horns.

These snakes are venomous and should be treated as dangerous. Their venom acts mainly on tissue and blood, and a bite can cause serious local damage along with systemic effects. Bothriechis are not aggressive and generally rely on camouflage and stillness, but their arboreal habit puts them at face and hand height in forest and on plantations, so unintended encounters happen. Never handle a wild venomous snake and never assume one is harmless because it is calm. A bite from any pit viper is a medical emergency: keep the person still, get to professional care immediately, and in the US contact Poison Control at 1-800-222-1222 or call local emergency services.

Ecologically, Bothriechis are ambush predators that wait motionless among branches for prey to pass, taking lizards, frogs, small mammals, and birds depending on species and age, with younger snakes often using the tail tip as a lure. Like most pit vipers they are live-bearing, giving birth to fully formed young rather than laying eggs. They are largely nocturnal and slow-moving, conserving energy between meals and depending on concealment rather than flight, which is part of why they remain hidden in plain sight in the forests they call home.