It is a reptile of crocodile, commonly known as pheasant, subminiature snake and flat-necked snake. They are distributed in Myanmar, Thailand, Cambodia, Laos, Vietnam, India, Sikkim, Malaysia, Indonesia and Fujian, Guangdong, Hongkong, Hainan, Guangxi, Sichuan, Guizhou and Yunnan in Chinese mainland, and most of them live near ditches in agricultural areas. Its upper survival altitude is 2250 meters. The model origin of this species is Java, Indonesia.

Like cobra and other poisonous snakes, the red-necked snake is an enterprising snake. Ecological habits: living near ditches in agricultural areas, moving during the day and feeding on frogs; When disturbed, the front of the body expands flat, the local skin expands, and the scales on the back are scarlet, which has warning and threatening effects. 1February, 1998, China Ophthalmology (2nd Edition) also failed to classify the red-necked snake as poisonous.

However, this snake has caused many serious injuries and even deaths in China. The fangs of Agkistrodon halys are located at the back of the mouth, which are posterior fangs, not more advanced tubular teeth. They need to be bitten deeply and chewed before injecting venom. Generally, there is no serious reaction after being bitten, and most of them are docile, so they have not attracted enough attention. There is no corresponding serum for Agkistrodon halys bite, and it can only be treated by dialysis at present.

Arboreal, burrowing. Daytime activities are mostly found near ditches in agricultural areas, mainly feeding on frogs, toads and tadpoles, but also eat small fish, insects, birds and rats. The snake is widely distributed and has strong adaptability.

Distributed in Bangladesh, Bhutan, Brunei, Cambodia, China, India, Indonesia (Java, Kalimantan, Sumatra), Lao People's Democratic Republic, Malaysia, Myanmar, Nepal, Thailand and Vietnam.

China is distributed in Guangdong, Guangxi, Fujian, Hongkong, Hainan, Sichuan, Guizhou, Yunnan and other provinces.