Although walking stick insects do not have a venomous sting or bite, some species can discharge a milky acidic spray from glands at the rear of the thorax. They can spray it accurately at predators at a range of up to two feet.
The acidic compound can provoke an intense burning sensation and cause temporary blindness if it reaches the eyes. In addition to spraying, walking sticks have several other defenses; they can discharge unpalatable blood from their leg joints as well as regurgitate a foul liquid. The best-known defense of the walking stick is the insect's ability to mimic twigs.