The adult is a clearwing moth, with the forewings brown and the hindwings clear with brown borders. The body mimics that of a wasp, brown with yellow markings. Eggs are deposited individually on grape leaves or weeds, or dropped on the ground close to the trunk. The larvae hatch and burrow into the soil, find their way to the roots and crown, and feed on them. Larvae continue to feed within the vine's root system for about 22 months.
Mature larvae move to places just under the surface of the soil and pupate in earthen cells.
Adults start emerging in July and continue to emerge through August. Life cycle of grape root borer. Damage Symptoms Larvae attack the roots and crown of grapevines. They tunnel into the roots or crown and feed internally. Feeding and boring weaken the grapevine and may eventually kill it.