Scales are weakly keeled rather mostly smooth. Triangular head broader than neck; round snout; eye has vertical pupil. Heat sensory pits are present between nostrils and eyes. Tail is short. Upper side body is generally colored in various shades of green; males are darker than female. Males have the thin white stripe on lower partial side of the body. Sometimes that white stripe is bordered from below with reddish brown or red line. Generally absence of this white stripe is noticeable in female, if present, then indistinct or distinct. Males possess a white line below eye alongside head. Area below eyes and lip scales are yellowish, pale green or blue-green. Lip scale edges bordering mouth, narrowly lined in white. Different color shades are noticed for eye, yellow, yellowish-brown, pale red, orange or blood red. Underside is glossy pale green, yellowish, bluish or whitish.
Length: 0.41ft at birth to maximum 3.25ft.
Scales in 21 or 23 rows at midbody. Ventrals 149-173; anal usually entire; subcaudals 48-78, paired. Supraoculars narrow, sometimes large, 8-12 scales on a line between them; internasals distinctly larger then adjacent scales on upper surface of head, touching, or separated by a scale. Supralabials 7-13, the first almost entirely united with the nasal.
Habitat and Reproduction
They are found in forest areas, tea plantation and around human habitation. Feeds on frogs, lizards, birds and small mammals. The White lipped pit viper is ovoviviparous and produces a litter of 7-16 young ones.
Bite and Venom
White-lipped pit viper is capable of delivering fast strikes. Swelling and pain are after effects of bite. Bite from large snake could be fatal. The venom is hemotoxic.
In India White lipped pit vipers are recorded from Darjeeling of West Bengal and Dibrugarh, Assam. Later, in a recent study Andaman & Nicobar Islands was included for their distribution. Recently for the first time individuals of this species are observed in the dense forests of Jashpur District in Chhattisgarh. This is recorded from China, Bangladesh, Myanmar, Macao, Taiwan, Laos, Vietnam, Thailand, Indonesia and Cambodia.
Loss of habitat and deforestation poses serious threat to this species.