Six families of largely arboreal birds make up the order Piciformes, the best-known of them being the Picidae, which includes the woodpeckers and close relatives. There are about 67 genera in the six families and a little over 400 species. In general, the Piciformes are insectivorous, although the toucans mostly eat fruit and the honeyguides beeswax. Nearly all Piciformes, like the owls and parrots, have zygodactyl feet—two toes forward and two back, an arrangement that has obvious advantages for birds that spend much of their time on tree trunks.