This fly creates an elongate, light green to reddish-green pouch gall in major leaf veins. When the fly maggot completes feeding, the gall on the upper surface of the leaf dries and cracks open (Fig. 71). The gall is 0.1 to 0.3 inch (3 to 8 mm) long. Infestations usually become evident in June and galls open sometime during July.