Wagler's pit viper is perhaps the most well-known of the green, arboreal pit vipers to be found in the region. This is a snake of primary forest, mature secondary forest and mangroves. It is active by night; by day it generally lays coiled high in the trees.
The term "pit viper" refers to heat-sensing "pits" which occur on each cheek - these are used to locate prey. As with other pit vipers, this species has haemotoxic venom, meaning it is poisonous to the blood system.
The species can be identified by the triangular head. Juveniles are mainly light green with narrow pale bands, and adults are dark green with thicker yellowish bands.
Wagler's pit viper ranges from southern Thailand, Peninsular Malaysia and Singapore to Borneo, Sumatra, Sulawesi and the more southerly islands of the Philippines.