Quercus macrocarpa
Stem galls, woody stem swellings
Irregular, covered with normal bark, at base of last year's growth. Seen at Joliet, IL in May.
- LH Weld: (1959) Cynipid galls of the eastern United States©
Reference: https://www.biodiversitylibrary.org/item/273718#page/116/mode/1up