Respect where respect is due: we humans may be mighty, but there’s still a foe that regularly dodges our best efforts to kill it: the fruit fly. Over millennia of evolution, fruit flies have adapted to burn their pursuers with enviable agility. Now researchers have built a robotic doppelganger that can twist and bank with astonishing speed. With two pairs of wings beating 17 times a second, it has a wingspan of over a foot and weighs just an ounce.