Unidentified gall on water oak

These photos are from Maryland, North and South Carolina, Texas, Alabama, Georgia, and Florida. The same galls have also been found in Louisiana, per Martin Hauser's comment on this blog post, and Ken Childs has found them in Tennessee.

Galls have been found from September to November.

Hosts include Shingle Oak, Quercus imbricaria, Water Oak Quercus nigra, and Cherrybark Oak Quercus pagoda (gallformers.org).

These galls are around 3/16" to 1/4" in height and are found on the upper surface of water oak leaves. There do not appear to be any references to them in the gall literature. In March 2021, Charley Eiseman dissected a couple that were collected by Tracy Feldman the previous fall and found dried midge larvae inside. These were sent to Ray Gagne, who reported: "The two larvae are typical Polystepha and presumably a new species (I am judging from the shape of the galls). The species will most likely have one generation per year with adults appearing in spring."

Gallformers