Biological notes.—Galls (Figs. 9–10) occur on branch tips and are 2–3 mm long and formed of two opposing, cuplike, fused, hemispherical leaves. The one to several larvae inside are yellow with green guts. When full-grown, larvae force their way through the solid tip of the gall and drop to the soil. The persistent galls then turn purple or brown. Galls began to appear in early July in eastern West Virginia and became much more common as the season progressed. New galls continued to appear through the beginning of September.

Distribution.—I found this species in Maryland and West Virginia on P. tenuifolium, in Maryland on P. verticillatum, in Connecticut on P. virginianum, and Virginia and North Carolina on P. flexuosum. I did not find this species on P. muticum growing among P. tenuifolium in Laurel, Maryland, or on P. muticum in Clarksburg, Maryland