The Mysterious Light Fly: A Beneficial Predator of June Beetles

That large, inch-wide insect on your window screen is a light fly (Pyrgota undata), a member of the family Pyrgotidae. Despite its intimidating appearance, it doesn’t sting. These flies are attracted to lights at night—a rare trait among flies.

Fascinating Life Cycle

The female light fly catches female June beetles in midair, wrestles them, and deposits an egg in the beetle’s abdomen. The fly larva then parasitizes the beetle grub, eventually killing it. This unique behavior helps suppress June beetle populations naturally.