DESCRIPTION: The elongated galls that are found on the underside of the hostplant are created by a midge.  The galls measure up to 5cm  in length and distort the appearance of the leaf. Areas infested can be seen on both sides of the leaves with the upper areas pale in colour. Each swelling contains a white larva. There is one generation per year with the larva overwintering in the soil. Galls can also appear on the fruits of the hornbeam. DISTRIBUTION: An occasional species but sorely under recorded. HABITAT: Found on undersides of leaves along the midrib or side veins of Hornbeams.