Theretra indistincta is a moth of the family Sphingidae. It is known from Queensland, Papua New Guinea, Indonesia and the Bismarck Archipelago. Adults are brown. The forewings each have a small dark spot near the middle, and a faint dark subterminal line. The hindwings are darker but each has a pale margin. They have pink antennae. The larvae feed on Vitis vinifera. They are green or brown, with a row of white encircled green spots with white centres along each side, one per segment. The tail has a stout red horn curving back with a black tip. Pupation takes place in a mottled brown pupa.