It takes just one gene to rule them all. With that gene, a voodoo virus compels its caterpillar hosts to emerge from their shady hideaways, climb en masse to the tops of trees, deliquesce and fall as a rosy rain of viral particles on their fellow healthy caterpillars. Soon, they too will make the climb of doom. The virus is known as baculovirus and its unsuspecting host the gypsy moth caterpillar. Like many other mind-controlling viruses, fungi and bacteria that, for instance, turn ants into zombies and make rats unusually fond of cats, baculovirus can selfishly change the behaviour of its host.
