(Cyzenis albicans)
Cyzenis albicans is a species of fly in the family Tachinidae. A parasitoid, it lays its eggs on leaves of oak, maple, birch and other trees, so that when the leaves are consumed by the larvae of the host winter moth, the eggs hatch inside the larvae. The fly is native to Europe and Asia but has been introduced into North America as a biological control agent of the invasive winter moth.