In the spring before chestnut buds normally break the gall wasp larvae begin to mature and convert the bud into a gall. Galls develop in 7-14 days and often contain portions of developing leaves, stems,petioles, and flowers. The larvae feed 20 to 30 days within the galls before pupating. After emergence, which is complete in approximately 3 weeks, the female lays 3-5 eggs in a cluster inside the buds. The eggs hatch in 40 days.
Larval growth is very slow through the autumn and winter.
Spread of the gall wasp occurs as a result of movement of infested twigs or shoots, or by flight of the adults. After adult emergence, the gall dries, becomes woody and remains attached to the tree for several years. Pruning and destroying infested shoots may slow the spread of the insect.