Gall formed by two leaves appressed together to form a blister gall...Asphondylia solidaginis BeutenmĂźller
Each of the two leaves involved forms one half of the unicellular, ovoid, 4â5 mm diameter, white-fungus-lined gall...
â- Raymond J. Gagne: (1989) The plant-feeding gall midges of North AmericaŠ