When compared to other insects protected by venomous stingers or capable of rapid flight, crickets seem unarmed and defenseless. Despite this, crickets persist in environments around the world, cheerily chirping the night away. While the various species survive because of their high reproductive rate, individuals survive for as long as they can by hiding, fleeing and fighting back against predators.
Hiding and Camouflage
Many crickets are nocturnal, thus reducing their exposure to diurnal birds, lizards and other predators. During the day, these crickets will hide in deep vegetation, under some sort of cover or inside a burrow. Those that are diurnally active are generally very well camouflaged to match the leaves, grass or leaf litter they inhabit.
Once a predator has spotted a cricket, running and jumping become the cricket’s primary defense mechanism. Many crickets detect minute air current variations—such as would be made by a predator blocking the wind, or breathing on the cricket—and respond to this type of stimulation by fleeing. In 1995, researchers Eran Tauber and Jeffery M. Camhi investigated these defensive tactics in the field cricket (Gryllus bimaculatus). Publishing their results in “The Journal of Experimental Biology,” the pair found that the cricket’s defensive responses invariably took one of three forms: turning, jumping, or turning and then jumping.
While crickets are shy and retiring animals that prefer to flee rather than fight, they will bite predators as a last resort. Some crickets—notably Jerusalem crickets (Stenopelmatidae)—have large jaws capable of delivering a significant bite. In some cases Jerusalem crickets will flip on their backs and open their jaws wide in an attempt to dissuade a would-be predator.
Releasing Their Legs
If a predator grasps a cricket by the leg, the cricket will often release the leg in order to escape. Despite the obvious benefit of the behavior—a five-legged cricket can pass on more genes than an eaten cricket can—it is not a simple, involuntary process but a complicated decision the insect must make in the heat of the moment. Losing a leg reduces the insect's fitness; a missing back leg reduces its jumping ability, while a missing front leg can prevent some crickets from mating, as their hearing structures are located on their front legs. Entomologists Philip W. Bateman and Patricia A. Fleming investigated leg autotomy in field crickets. Publishing their results in a 2005 issue of “Biology Letters,” the researchers demonstrated that crickets exercise control over leg autotomy, and use different criteria to decide whether to jettison a given leg. The data generated by the study showed that the leg’s position, the cricket’s gender and reproductive history as well as the number of legs that have already been lost are all factors that affect a cricket’s decision.
- Biology Letters: Sex and the Single (-eared) Female: Leg Function, Limb Autotomy and Mating History Trade-Offs in Field Crickets (Gryllus bimaculatus)
- What's Bugging You?: Backyard Monsters? Nope, Jerusalem Crickets
- Journal of Experimental Biology: The Wind-Evoked Escape Behavior of the Cricket Gryllus bimaculatus: Integration of Behavioral Elements [PDF]
- University of Nevada, Reno: Insect Defenses [PDF]