Rough Oak Bulletgalls

I received several complaints this past week from homeowners and professionals about large numbers of stinging insects buzzing oaks in Ohio landscapes. The most recent involved an oak next to a Columbus playground.

Several stem galls on oaks (Quercus spp.) that are produced under the direction of gall wasps (family Cynipidae) are called “bulletgalls” owing to their bullet-like shapes. Two of the most common found in Ohio are Rough Oak Bulletgalls induced by the cynipid wasp, Disholcaspis quercusmamma, and Round Oak Bulletgalls induced by D. quercusglobulus.

Rough oak bulletgalls are rising from oak stems in Ohio accompanied by their entourage of bodyguards. The galls are found on oaks in the white oak group with burr (Quercus macrocarpa) and swamp white oak (Q. bicolor) most commonly affected. The "mature" galls are commonly covered in black sooty mold.

Dave Shetlar (Professor Emeritus, OSU Entomology) and I have recently observed newly developing oak rough bulletgalls in central and southwest Ohio, respectively. The galls are produced under the direction of the gall wasp Disholcaspis quercusmamma (family Cynipidae). We're also starting to see the gall's security detail, but more about that later.