Filbertworm overwinter as larvae in silky cocoons under leaf litter and cracks in the tree bark or sometime in the soil where they pupate. Then adult moths begin emerging from pupae from June through October. After mating, female moths lay eggs singly near developing young hazelnuts. These eggs hatch within 10-12 days into small larvae that burrow into the nuts and start feeding on the kernel. These larvae continue feeding inside the nuts for over 2 weeks and then exit the nuts for overwintering or pupation in the soil or under leaf litter and life cycle continues.