Stick insect Defences Secondary defences
A number of species are equipped with glands at the front which release chemical compounds. These chemicals may give off unpleasant smells or cause a stinging, burning sensation in the eyes and mouth of a predator. Recent research suggests they manufacture their own chemical defense substances. Some species employ a shorter-range defensive secretion, where individuals bleed reflexively through the joints of their legs and the seams of the exoskeleton when bothered. The blood contains distasteful additives. Stick insects, like their distant relation the grasshopper, can also discharge the contents of their stomachs through vomiting when harassed, a fluid considered uneatable by some predators.