Calloselasma rhodostema, Malayan Pit Viper. Deadly venomous snake from Thailand.

Malayan Pit Viper – Venomous – Very Dangerous

Adult Malayan Pit Viper in situ, found in a culvert in Krabi, Thailand.
Adult Malayan Pit Viper in situ, found in a culvert in Krabi, Thailand.

(Page Updated: 6 September 2016)

Calloselasma rhodostoma (Malayan Pit Viper, Malaysian Pit Viper)

Thais say: Ngoo gap pa

Length: Usually less than 1 meter. Female Malayan Pit Vipers are the larger and fatter snakes. Males of the species don’t make it to 1 meter long.

Range: Thailand, Laos, Cambodia, Java, Sumatra, Malaysia, Vietnam, Burma, and China.

Notes: These vipers are similar to North American “copperhead” snakes. They prefer dry, flat areas. They are known as lazy snakes. They may not move out of the way at all if someone is walking right toward them. After they bite they are known to remain in the same location. There are thousands of bites per year in Malaysia and Thailand from this snake.

These snakes are so dangerous when handled because they are not consistent with their behavior. One day they will be calm. The next, or the next 10 minutes – they will violently strike out lightening fast. Their preferred habitat is under dry leaves, wood, or rocks. They are active during the night mostly, especially during rain.

Juvenile (neonate) Malayan Pit Viper with white-tipped tail.
A neonate Malayan Pit Viper showing the white-tipped tail it shakes to bring prey closer.

Nickname: Finger rotters – given by Al Coritz, Viperkeeper on YouTube. If they get you in the finger – you’ll likely lose part of your finger, hand, or arm without immediate care.

Habitat: Forests, rubber plantations, bamboo patches, farmland, grassland. Often lies in the short or long grass. These are terrestrial snakes that I’ve never seen climb anything.

Active Time? Day if cloudy and/or rainy, and night.

Food: Mice, frogs, lizards. Predominantly rodents.

Malayan Pit Viper from southern Thailand
Calloselasma rhodostoma. Malayan Pit Viper. Usually under a meter, and thick. Very common. Very dangerous.

Defensive Behavior: Partially coiled with neck in an “S”. Their strike is very fast. Their fangs are long – and in the front of the mouth. Some strikes are short, others involve the whole body as it “jumps” at the same time it strikes. Don’t underestimate the distance this snake can reach when striking. Also, this snake is VERY good at striking behind its head. Watch the video.

This pit viper has the longest fangs of any other snake in Thailand – including the Siamese Viper (D. siamensis).

Malayan Pit Viper (Calloselasma rhodostoma) skull showing fangs, jaws, and dentition.
Malayan Pit Viper (Calloselasma rhodostoma) skull showing fangs, jaws, and dentition. Skull is at Queen Saovabha Memorial Institute in Bangkok, Thailand.

Venom Toxicity: Very toxic. Venom is necrotoxic – it destroys all cells it comes in contact with – red blood cells, muscle, ligaments, and bone. With a quick hospital visit after a bite you may just lose part of your finger, or some tissue where the bite occurred. The venom causes a bite victim to bleed from body orifices – eyes, nose, mouth, ears, sexual organs, and sometimes fatally in the brain. Most people don’t die if they go to the hospital. Deaths occur when bite victims delay seeking medical treatment. There is antivenom for this snake.

If you are bitten by this snake, do NOT wrap a tight band around the bite location. That will stop the venom from moving, from being diluted, and the tissue will suffer much more destruction.

Offspring: Lay eggs. Female guards them. Young are about 9 inches long and fast and thin. They are fully able to bite, and have full strength venom.

Malayan Pit Viper Eating Mouse Video – close up of large fangs, strike, etc.

Malayan Pit Viper Scientific Classification

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Subfamily: Crotilinae
Genus: Calloselasma
Species: C. rhodostoma

Binomial Classification:
Calloselasma rhodostoma

Video – Malayan Pit Viper Showing How It Can Strike Backward VERY Accurately.

Video – Malayan Pit Viper Color Variety in Thailand


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About Vern Lovic

Snake posts by Vern Lovic. Amateur herpetologist roaming about Thailand on field herping tours and events to find king cobras, kraits, vipers, corals, keelbacks, and other snakes native to Thailand. FYI - Thailand has over 200 snake species. Here's our latest book with detailed information on Thailand's 35 Deadly Snakes. "Is That Snake In Your House Dangerous? Identify Deadly Thailand Snakes In Under 5 Minutes!" INFO HERE.

13 thoughts on “Malayan Pit Viper – Venomous – Very Dangerous”

  1. That wasn’t a mouse, that was a hamster.. Lol hope that wasn’t the girlfriend or the kids pet placed in there by mistake!

    If it was a mouse it would have had a longer tail.

  2. I’m just reading about the pit viper as I was very silly a few days ago drunk coming out a bar in hau him Thailand and seeing the pit viper all coiled up and decided to tease it not knowing what it was but lucky for me it never strikes me before someone pulled me away and explained in broken English what this snake was and what it can I’m horrified to my stupidity and thanks to this web site I now know to keep away if see anymore of this snakes

  3. Nearly trod on a viper (looked kind of like this) at night in Laos years ago. Was barefoot waiting for a sandwich and there it was. The sandwich lady chopped it with her meat cleaver. Lucky escape…..not for the viper.

  4. I had an encounter with this early one morning last week while sweeping up the leaves in my garden in Bangsaen. I was concentrating on sweeping the area around my feet and was paying no attention to my immediate surroundings when I suddenly I came upon it. And there is was at my feet! It must have seen or sensed I was walking nearer and nearer but obviously had made no attempt to move from its curled position. I was only aware that it was there when I saw it jump at the broom which I guess might have actually touched it. I moved back pretty dam quickly as I was aware it was dangerous and cursed myself for being so careless. The snake itself returned to its previous curled position and made no attempt to leave. Pretty much sums up the characteristic of this species I guess.

    1. Classic Malayan pit viper… sit there and wait for something to come by – even people. Good that you knew what it was and gave it some space fast!

  5. I recently found two snakes in our water tank about 30 cm long with red bellies with pronounced black spots. The snakes to me looked like keelbacks, but it was hard to tell due to their small size. My Thai wife says they were Malayan pit vipers, but I cannot find any information or pics on this anywhere. Does anybody here have a clue? I live in the Tak province, not far from Sukhothai. Any leads would be greatly appreciated.

    1. Sounds like one of the kukri snakes, or a coral snake. Explain more about the red belly and black spots – and where are the black spots? What does the top look like?

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