This species has two generations a year that induce distinct bud galls on different Solidago species ... The much more conspicuous summer-generation gall of this species on S. juncea (the host was incorrectly identified as S. canadensis in the original description) is a rosette bud gall that is found in great numbers... They are usually composed of 15–30 individual units, each with a single larval chamber that is surrounded by shortened leaves and lined internally by white mycelium. These units form a spherical structure on shoot tips.

[please refer to this paper for many more details of gall biology]

Bud or flower gall...
Galls made up of bud leaves, often as rosette on foreshortened stem...
Rosette galls made up of 25 to hundreds of leaves...
Gall single or composite, the internal leaves not linear and narrow, merely shortened...
Larva in central cell of rosette gall, the inside lined with white mycelium of symbiotic fungi...Asphondylia monacha Osten Sacken

Osten Sacken gave as host of this species Solidago altissima, but the type galls appear to be on S. juncea...