But surprisingly, they can do that without ever physically touching the brain itself. Hughes’s team found that fungal cells infiltrate the ant’s entire body, including its head, but they leave its brain untouched. There are other parasites that manipulate their hosts without destroying their brains, says Kelly Weinersmith, from Rice University. For example, one flatworm forms a carpetlike layer over the brain of the California killifish, leaving the brain intact while forcing the fish to behave erratically and draw the attention of birds—the flatworm’s next host. “But manipulation of ants by Ophiocordyceps is so exquisitely precise that it is perhaps surprising that the fungus doesn't invade the brain of its host,” Weinersmith says.