When in the resting attitude by day, the insects resemble pieces of twig and are difficult to distinguish from the surroundings.

[1] Like other stick insects, Pterinoxylus spinulosus is a herbivore,[2] and in captivity it can be maintained on a diet of guava leaves (Psidium sp.).

The first is crypsis; the insect is nocturnal in its habits and both adults and nymphs spend the day stationary in a resting position with the front legs extended forward beside the head and the other two pairs of legs folded tightly to resemble side twigs on a dead stick.

This arrangement of limbs conceals the head and may deceive a visually-hunting predator so that the insect remains unnoticed.

The wings are translucent and dark brown, with black venation, and produce metallic reflections in sunlight.