The agency has a fascination with animals – not cutting them up but copying them, a field called biomimetics. The gecko offers a model for figuring out a way to walk up walls. The octopus is an expert at camouflage. The blur of a fly's wings may someday be replicated in combat aircraft. And since dogs are the only mine detectors that can distinguish between explosives and metal, the agency has reportedly spent $25 million trying to create an artificial dog nose. But the real military rock star is the cockroach. Unrivaled in locomotive sophistication, the cockroach has six active legs that simultaneously perform three distinct tasks: The rear legs drive it forward, the middle two turn and lift the body during climbing, and the front legs act as sensors to determine where the next footholds will be. When a roach has to climb over something, it automatically selects from thousands of possible adjustments.
"They are the decathletes of the insect world," says Roger Quinn, professor of mechanical and aerospace engineering at Case Western Reserve University. Quinn and his colleagues are at work on their fifth roachbot. Called Ajax, it's a full three feet long, weighs 33 pounds, and has artificial muscles. Within five years, Ajax's progeny could support troops in the field by toting supplies. As the models grow more sophisticated, soldiers should be able to ride them, or use them to ferry heavy equipment or even casualties. As one DARPA manager says, after studying the cockroach, "We're not sure the wheel's the way to go."