Like a few other Andricus
species, forms galls on the undersides of veins of leaves in the white oak group, composed of seedlike cells in groups, covered by wool. Felt (2)
describes the galls as "oval, rather thick-shelled, brown leaf vein gall, at first woolly, later naked, length 1/8 inch, diameter 1/16 inch, on swamp white oak [Quercus bicolor
]." Krombein et al. (3)
also list bur oak (Quercus macrocarpa
) as a host. Weld (1)
clarifies that the galls drop with the leaves in the fall and the wool weathers away during the winter.