Anopheles dirus occurs in areas of tropical forest that extend eastward from central Myanmar through much of Thailand, Laos, Cambodia and Vietnam. It also occurs on Hainan Island of China.
It is typically an inhabitant of foothills, forests and forest fringes, but will also invade orchards and plantations.
Larvae inhabit small, shallow, temporary, shaded bodies of fresh water such as:
They are also found in wells in hilly or mountainous regions with:
This indicates that the species has adapted to environmental change brought about by humans. It is thought that the favoured habitat was elephant footprints before these animals, and the logging industry, diminished.
The adult females readily feed on humans inside and outside houses, and are highly competent vectors of malaria parasites.