Reptiles
Fer-de-lance
Bothrops asper · also called fer-de-lance, terciopelo, barba amarilla
The fer-de-lance is not the most venomous snake in the Americas, but it is the one that hurts the most people. It is large, fast, superbly camouflaged, produces enormous litters, and lives precisely where people farm — and its venom rots flesh. In much of Central America, “snakebite” effectively means this animal.
Overview
The fer-de-lance (Bothrops asper), known in Spanish as terciopelo or barba amarilla, ranges from southern Mexico to northern South America, in lowland and mid-elevation forest, plantations, farmland, and along rivers. It is nocturnal, ambushes prey from coiled positions along rodent runways, and is a strong swimmer. Adults are patterned in browns, greys, and blacks that vanish into leaf litter.
A heat-guided hunter
Like all pit vipers, it has a heat-sensing pit between the eye and nostril on each side, sensitive enough to build a rough thermal image and strike a warm mouse in total darkness. Juveniles wave a bright yellow tail tip to lure frogs and lizards into range.
The venom
The fer-de-lance delivers a large dose of mostly haemotoxic, tissue-destroying venom. Bites cause intense pain, massive swelling, blistering and necrosis (frequently leading to amputation), internal bleeding, clotting failure, and kidney damage. Antivenom works, but the outcome depends on how fast it is given.
Why it is the problem snake
Bothrops asper causes the majority of snakebite injuries, amputations, and deaths across much of Central America — not because its venom is the strongest, but because it is abundant on farmland, camouflaged, nocturnal, quick to strike, and unwilling to retreat, and because agricultural workers meet it constantly, often unshod.
Status
The fer-de-lance is Least Concern and, unusually for a large snake, thrives alongside people — forest clearance creates the rodent-rich edge habitat it prefers. Its abundance keeps snakebite a serious, under-resourced rural health problem.
Fer-de-lance: common questions
Why is the fer-de-lance considered so dangerous?
It is a case of the wrong snake in the wrong place. Its venom is potent and delivered in large quantities, causing severe local tissue destruction (blistering, necrosis, often leading to amputation), uncontrolled bleeding, and kidney failure. But what makes it the leading cause of snakebite injury across Central America is where and how it lives — abundant on plantations, farmland, riverbanks, and the edges of villages, well camouflaged in leaf litter, nocturnal, and inclined to stand its ground and strike fast and far. Agricultural workers, often barefoot or in sandals, encounter it constantly. Antivenom exists and works, but access and speed of treatment vary.
What does "fer-de-lance" mean, and is it the right name?
The term is French for "spearhead" or "lance iron," referring to the snake's narrow, pointed head. Strictly, the name was first applied to a different species, Bothrops lanceolatus, from the Caribbean island of Martinique. The large mainland Central American snake covered here is Bothrops asper, and its widely used Spanish names — terciopelo ("velvet", for the skin texture) and barba amarilla ("yellow beard", for the pale chin) — are more precise. In practice English speakers use "fer-de-lance" for the whole group of large Bothrops vipers.
How does the snake hunt in the dark?
Like other pit vipers, it has a heat-sensing pit organ on each side of the face, between the eye and the nostril. These pits detect infrared radiation with enough resolution to build a crude thermal image, so the snake can locate, aim at, and strike a warm mouse in total darkness, guided almost entirely by the animal's body heat. It combines this with a forked tongue that samples scent trails. Adults ambush rodents from a coiled position along runways; young fer-de-lance wave a bright yellowish tail tip to lure frogs and lizards within striking range, a behaviour called caudal luring.
Is the fer-de-lance endangered?
No — it is one of the few large venomous snakes that has benefited from human land use. Clearing forest for pasture and crops creates the rodent-rich edge habitat it prefers, and it is common to abundant across its range and listed as Least Concern. This is the opposite of the situation for forest-dependent snakes. It does mean, though, that human–snake conflict is not going away, and snakebite from Bothrops asper remains a serious and under-resourced public health problem in rural Central America.