--- title: "South American Bushmaster (Lachesis muta) | AnimalTracks.wiki" description: "The longest of all vipers, able to aim a strike in the dark by body heat alone, from the only pit vipers in the Americas that lay eggs." image: "https://animaltracks.wiki/images/animals/south-american-bushmaster-1.webp" published: "2026-09-06" updated: "2026-09-28" --- # South American Bushmaster (*Lachesis muta*) > **Status**: Checked against 6 sources, listed under Sources below. > **Tagline**: The longest of all vipers, able to aim a strike in the dark by body heat alone, from the only pit vipers in the Americas that lay eggs. > **Soundtrack Vibe**: Latin Trap & Heavy 808s // ROSALÍA, "MALAMENTE" > **Soundtrack Links**: [Spotify](https://open.spotify.com/track/1B0BQaSRHxhI0AUlItY3LK) | [YouTube](https://www.youtube.com/watch?v=mw2XM-PSqXY) > **Vibe Match**: A bushmaster lies hidden under leaves until prey comes within strike range, and a warm body closer than 50 centimeters is enough to aim by heat alone. MALAMENTE builds the same held tension out of sparse handclaps and silence before the bass lands. ## Biological Superpowers & Stats - **Taxonomy**: *Lachesis muta* - **Danger Level**: Deadly - **Conservation Status**: Least Concern ([IUCN Red List](https://doi.org/10.2305/iucn.uk.2021-3.rlts.t62254a44946798.en)) - **Superpower**: Facial heat-sensing pits that let it aim a strike at a warm body within 50 centimeters with no other senses needed, backed by venom produced in quantities of up to 400 milligrams. - **Habitat**: Rainforest across the Amazon and Atlantic Forest, with pockets of humid forest in northeastern Brazil - **Diet**: Small rainforest mammals, especially the rice rat Oryzomys, and sometimes birds - **Tags**: reptile, rainforest, carnivore, venomous, nocturnal, predator ## Natural History & Behavior By day the South American bushmaster (*Lachesis muta*) rests in a burrow it did not dig, stolen from or shared with an agouti or an armadillo, and it moves infrequently and very slowly. Adults are usually well over 2.5 meters long and weigh 3 to 5 kilograms, and some of the longest reach about 3.5 meters, making it the longest of all vipers. The longest-lived on record reached 31.6 years in captivity. Its scientific name means "silent fate," a nod to the tail it shakes when threatened, though it has no rattle. ## Striking by Heat A bushmaster hunts at night by ambush, hidden under leaves or dense foliage until prey comes within range. A pair of pits between its eyes and nostrils reads infrared heat, and if a warm body comes within 50 centimeters, the snake can aim its strike from that heat signature alone, with no other senses involved. Its favorite meal in the wild is the small rice rat. Prey over 120 grams is usually struck, released and trailed by scent. Its venom is relatively weak next to its close relatives', but it comes in volume: up to 400 milligrams, one of the largest amounts produced by any snake, enough that even released prey usually dies within minutes. > **A Viper's Venom with Cobra Parts** Geneticists sequencing bushmaster venom genes found atypical molecules "never observed in the hundreds of Viperidae snakes studied so far," including one from a class of toxins described from Elapidae, the snake family that includes cobras and mambas. ## The Egg-Laying Exception Bushmasters are the only pit vipers in the Western Hemisphere that lay eggs. A female lays 8 to 12 white eggs, each a little larger than a chicken egg, coils her body around the clutch, and does not leave it for any reason until the eggs hatch roughly 78 days later. Hatchlings emerge at approximately 30 to 50 centimeters long with a bright orange or yellow tail tip used to lure prey, a color that fades as they grow older. ## Bites in Brazil A 2001 Brazilian medical review notes that most of the country's snakebites come from lanceheads and rattlesnakes, and that bites by Lachesis are rare. Their systemic effects can include low blood pressure, dizziness, darkened vision, a slowed heartbeat, abdominal cramps and diarrhea, grouped as a "vagal syndrome." The bushmaster lives in forest across the Amazon and the Atlantic Forest, with pockets of humid forest in Brazil's northeast, and the IUCN lists the species as Least Concern. ## Frequently Asked Questions ### How long do South American bushmasters live? Nobody knows how long one lives in the wild, where it is so secretive that many of its habits are unknown. The longest-lived on record reached 31.6 years in captivity. *(Source: [AnAge: The Animal Ageing and Longevity Database]())* ### Is the South American bushmaster the same species as the bushmasters of Central America? Many authors say no. The Central American bushmasters were described as subspecies of Lachesis muta, and many now treat them as full species: the Central American bushmaster, from southeastern Nicaragua to the Pacific coast of Colombia and Ecuador, and the black-headed bushmaster of southeastern Costa Rica. Lachesis muta keeps the rest of the range in South America. *(Source: [Animal Diversity Web, University of Michigan]())* ### How often does a South American bushmaster actually bite someone? Rarely, by Brazil's numbers. In the national figures for 1990 to 1993, Lachesis caused 1.4 percent of the snakebites whose snake genus was recorded, against 90.5 percent for Bothrops lanceheads and 7.7 percent for rattlesnakes. *(Source: [Pinho & Pereira 2001]())* ## Sources 1. [Lachesis muta (South American bushmaster). Animal Diversity Web, University of Michigan.]() 2. [Lachesis muta (Bushmaster or Mapepire Zanana). The Online Guide to the Animals of Trinidad and Tobago, University of the West Indies.]() 3. [AnAge entry for Lachesis muta. AnAge: The Animal Ageing and Longevity Database.]() 4. [Gutiérrez-Cárdenas et al. (2021). Lachesis muta. The IUCN Red List of Threatened Species 2021: e.T62254A44946798.]() 5. [Pinho & Pereira (2001). Ofidismo. Revista da Associação Médica Brasileira.]() 6. [Junqueira-de-Azevedo et al. (2006). Lachesis muta (Viperidae) cDNAs Reveal Diverging Pit Viper Molecules and Scaffolds Typical of Cobra (Elapidae) Venoms: Implications for Snake Toxin Repertoire Evolution. Genetics.]() *Published September 6, 2026. 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