In the forests of Madagascar there lives a primate with a lifestyle remarkably like a woodpecker's. Both the woodpecker and the primate, the rare and elusive aye-aye, bore through wood and probe cavities beneath the surface in their search for insect larvae. The woodpecker, of course, uses its beak for chiselling into the wood and its long tongue to extract its prey; the aye-aye, on the other hand, uses its incisor teeth to gnaw its way in and its narrow, elongated third finger to probe and scoop. Though the aye-aye's a strange way of feeding was first described over a hundred years ago, scientists have only now discovered how it locates the insects hidden inside the wood.

Dr Carl Erickson, of Duke University's Primate Centre, has been investigating the hunting skills of two captive males, Nosferatu and Poe, a female, and her infant daughter, Annabelle. He first tested whether they found insects just by looking for the telltale visual signs of their presence. For example, holes on the surface might indicate sites where female insects had entered the wood and laid their Dr Erickson presented the eggs with logs in which he had drilled several narrow holes. Some holes led to cavities containing worms, while others were blank dead-ends. The aye-ayes went straight for the cavities with food, gnawing through the wood and clearly not requiring the visual clues of surface holes. Perhaps the aye-ayes were locating the worms by their smell or the sounds they were making. But further tests showed that they didn't use these clues either. Logs in which the smell of the insects was prevented from leaking out presented no problem, and the aye-ayes also located dead (and therefore silent) worms.