Calloselasma rhodostoma (The Malayan Pit Viper) is a snake species that is found in many locations across Thailand. Here in Krabi, we can find it in many places.
If you would like to attempt to find this snake on your own in Thailand – read on.
If you have limited time, Book a Night Safari to find this and other snakes >
Calloselasma rhodostoma (Malayan Pit Viper)
Also known as: Malayan Ground Pit Viper, Siamese Pit Viper.
Go on a NIGHT WALK for SNAKES! >
Quick Snake Facts
Thai Name: งูแมวเซา – in English – ngoo maew sao (cat snake).
Local Name: Maew Sao
Average Length: 60-80 cm, with some individuals exceeding 1 meter
Geographic Range: Thailand, Malaysia, Indonesia, Cambodia, Vietnam, Laos, Myanmar
Conservation Status: Not currently listed on the IUCN Red List. There is an abundance of this species in Krabi and Thailand overall.
Antivenom Code: SAsTRC02
Physical Description
The Malayan Pit Viper is easily recognizable by its triangular head, thick body, and intricate brown and reddish-brown triangle patterns that provide excellent camouflage in leaf litter. Key identifying features include:
- Distinctive dark brown and light brown geometric triangular pattern along the body
- Keeled dorsal scales, giving a rough texture
- Large, heat-sensing pits between the eyes and nostrils
- Prominent triangular head, much wider than the neck
Habitat & Distribution
Elevation range: 0-800 meters
- Primary and secondary forests
- Agricultural areas and plantations
- Dry and semi-evergreen forests
- Found in Krabi, and nearby areas of Phang Nga, Surat Thani, Nakhon Si Thammarat, Pattani, and southern Myanmar
Where to Find the Malayan Pit Viper in Thailand
Surat Thani Province – Near Khao Sok National Park, this species is often encountered along the edges of trails and in dry, leaf-covered areas near forest borders.
Satun Province – At Thaleban National Park, this species is found resting in thick undergrowth near footpaths.
Krabi Province – The Tiger Cave Temple area has reported sightings, particularly in the dry wooded areas and at the base of limestone formations. Tourists have stepped on this snake in the leaves at the temple during daytime.
Phanom Bencha National Park – The snake is found in the leaf litter along shaded trails, particularly near water sources.
National Park at the Waterfall – Along trails leading to the waterfall, this species is often found resting on dirt or leaf-covered paths.
Best Time of Year to Find the Malayan Pit Viper in Thailand
The best time to find Malayan Pit Vipers is from April to January, during the wet season when humidity levels are higher. They can be found year-round, but they are less active during the hottest months of March and April.
Best Option for Finding the Malayan Pit Viper?
We can usually locate Malayan Pit Vipers throughout the year. If you are specifically targeting this species, ask us if we have current locations where they have been spotted. We can take you on a Night Safari to search for this and other reptiles.
OR, join us for a motorbike/scooter only Krabi Herping Tour covering Day and Night!
Malayan Pit Viper Behavior
Activity Patterns
- Primarily nocturnal but also active during cloudy days
- Prefers to remain hidden in leaf litter or under rocks during daylight and fully exposed at night
- Ambush and active forager – frequently found on the move at night.
Hunting & Diet
- Preys mainly on frogs, rodents, and lizards
- Uses heat-sensitive pits to detect warm-blooded prey
- Ambush predator, striking from a concealed position
- Is often eaten by King Cobras
Defensive Behavior
- Extremely defensive and quick to strike when threatened
- Often remains motionless, relying on camouflage
- Bites occur frequently when stepped on or accidentally disturbed
- Venom is highly potent and can cause severe tissue damage
Reproduction
- Viviparous (live-bearing)
- Gestation period: 5-6 months
- Litter size: 10-30 offspring
- Newborns are fully independent and have venom from birth
Venom & Medical Significance
Venom Characteristics of Calloselasma rhodostoma
- Potent hemotoxin that causes severe tissue destruction
- Can lead to necrosis, pain, and permanent disability if untreated
- Fatalities are rare but possible without medical intervention
Treatment
Malayan Pit Viper Antivenin is available at most Thai public hospitals:
Manufacturer: Science Division, Thai Red Cross Society
Provider: Queen Saovabha Memorial Institute
Address: 1871 Rama IV Road, Pathumwan, Bangkok 10330
Contact: +66-2-252-0161 to 0164
Taxonomic Classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Genus: Calloselasma
Species: Calloselasma rhodostoma
Conservation Notes
While not currently listed as threatened, the species faces increasing pressure from:
- Habitat loss due to deforestation and agriculture – in Krabi and other locations.
- Road mortality, especially near forested areas
- Human-snake conflicts in developed regions
Although it is common in its range, the Malayan Pit Viper plays a crucial role in controlling rodent populations. Educating locals about its behavior and medical treatment options can reduce unnecessary killings and snakebite fatalities.
Go on a NIGHT WALK for SNAKES! >