Trimeresurus macrops

Venomous and Dangerous!

Large-eyed Pit Viper Trimeresurus macrops
Large-eyed Pit Viper in Laos (photo by Gernot Vogel)

Large-eyed Tree Viper Cryptelytrops macrops
Another view of Large-eyed Pit Viper (photo by Gernot Vogel)

Large-eyed Pit Viper Trimeresurus macrops  Khao Yai Randy Ciuros
Large-eyed Pit Viper in Khao Yai (photo by Randy Ciuros)

large-eyed green pit viper Cryptelytrops macrops
Large-eyed Pit Viper at Queen Saovabha Snake Farm

Trimeresurus macrops (Big-eyed viper)   Kevin Messenger Nakhon Ratchasima
Large-eyed Pit Viper in Nakhon Ratchasima Province (photo by Kevin Messenger)

Large-eyed Pit Viper Cryptelytrops macrops (Big-eyed viper)   Kevin Messenger Nakhon Ratchasima
Another shot of Large-eyed Pit Viper (photo by Kevin Messenger)

Big-eyed Pit Viper Cryptelytrops macrops
Front view of Large-eyed Pit Viper (photo by Kevin Messenger)

Large-eyed Pit Viper Trimeresurus macrops
Large-eyed Pit Viper (photo by Tom Charlton, venomlogic.com)

Big-eyed Pit Viper Trimeresurus macrops
Large-eyed Pit Viper (photo by Tom Charlton, venomlogic.com)

Large-eyed Green Pit Viper Cryptelytrops macrops
Large-eyed Pit Viper (photo by Tom Charlton, venomlogic.com)

English name: Large-eyed Pit Viper (aka “Large-eyed Tree Viper”, “Large-eyed Green Pit Viper”, “Big-eyed Pit Viper”)
Scientific name: Trimeresurus macrops (formerly Cryptelytrops macrops)
Thai name: Ngu Kieo Hang-mi Ta To

Description: To 71cm long. A slender snake with a broad, somewhat short triangular head. Heat-sensing pits are located on the head between the nose and each eye. Body is dark green to bluish-green above and paler bluish-green to pale blue below. Head is green above and the lips and throat are bluish-green. Eyes are large and yellow to orange. Tail is reddish-brown.

Similar Species: White-lipped Pit Viper is white, yellowish, or pale green on the lips and throat and has a longer head and smaller eyes.
Mangrove Pit Viper is brown, gray, olive, or greenish-yellow and has dark blotches.
Golden Tree Snake has a narrower, non-triangular head and black markings.
Long-nosed Whip Snake is more slender and has a longer, narrower head that ends in a point.

Habitat: Can be found in forest, shrubland, plains, agricultural areas, and gardens. Usually found off the ground in trees or bushes but will also hunt on the ground at night.

Place in the ecosystem: Eats frogs and lizards, and occasionally mall rodents and birds as well. Is eaten by birds of prey and larger snakes.

Danger to humans: The Large-eyed Pit Viper has a dangerous bite and should be taken seriously. Bites can result in intense pain, swelling, necrosis of flesh, and in some cases severe systemic bleeding. Fatalities are very rare but local damage can be lasting. Anyone who is bitten by a pit viper should be taken to the hospital as quickly as possible. See “Interesting facts” for more information.

Conservation status and threats: No known conservation threats.

Interesting facts: Southeast Asian Pit Vipers are not as deadly as the local cobras, kraits, and true vipers, but still can do some damage. The Large-eyed Pit Viper and White-lipped Pit Viper are together responsible for 40% of all snakebite hospitalizations in Thailand.

Thailand’s pit vipers have a “hemorrhagic” venom that causes pain, swelling, coagulopathy, and some tissue damage. In serious cases severe coagulopathy, internal bleeding, and necrosis of the flesh can develop. Pit Viper-specific antivenom is available and should be administered as soon as possible to relieve symptoms and decrease long-term effects.

If you or someone you are with is bitten by a Large-eyed Pit Viper, the most important steps are to:

1) Keep the victim calm, having them lie down with the bite mark below the heart if possible.
2) Take a picture of the snake to confirm identification for the hospital.
3) Get the victim to a hospital immediately where professional treatment can take place and antivenom can be given.

References:
Queen Saovabha Memorial Institute: Snake Farm
A national hospital-based survey of snakes responsible for bites in Thailand
Snake Bites and their Treatment
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
Snakes of Thailand and their Husbandry