Insects use a variety of defense mechanisms to avoid predation, including chemical defenses, running, flying, mimicry and camouflage. However, these are only a few of the tactics and strategies employed by the group as a whole.
North Carolina State University explains that when a predator grabs a leg of some insect species, such as crane flies, the insect can break off the appendage. Called autotomy, this technique is also employed by walking sticks, grasshoppers and other long-legged species. Some insects regenerate their lost limbs, but even among those that don't, the missing appendage usually isn't a serious burden.
Other species, particularly a number of caterpillars, use bristles, spines or hairs to defend themselves. Some of these hairs dissuade predators through mechanical means. Contrastingly, other hair types, such as the spines of saddleback caterpillars, induce pain or itching upon contact. Such structures are called urticating hairs.
Other insects, such as the familiar wasps, bees and ants, produce venom that is delivered through a hollow stinger. Located at the back of the abdomen, these stingers are actually modified ovipositors. The venom used by these insects often causes pain, but, in some cases, it can also cause an allergic reaction in the predator.