An ant-decapitating fly (Phoridae: Apocephalus sp.) pursues a carpenter ant (Camponotus chromaiodes). If the fly succeeds in laying an egg in the ant, the young larva will consume the ant's tissues, eventually killing it. The fly then crawls into the ant's head capsule, which typically falls off and serves as a protective case for the fly's transition to adulthood. Sand Ridge State Forest, Illinois, USA.