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

Malayan Pit Viper – Venomous – Very Dangerous

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

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.

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.

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.

Venom Toxicity: Very toxic. Venom is cytotoxic – 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. 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.


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

Binomial Classification:
Calloselasma rhodostoma

Malayan Pit Viper video:

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About Vern Lovic

All posts by Vern Lovic. Amateur herpetologist roaming about Thailand on field herping tours to find king cobras, kraits, vipers, coral snakes, and other snakes native to Thailand. FYI - Thailand has over 200 snake species with more than 60 of them venomous and dangerous to humans.

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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