Galls of G. inclusa are called "rice-grain" galls because of their size and shape. The gall clusters develop only in the basal half of the internode and protrude inwards from the internode wall (Skuhrava and Skuhravy 1981). The first generation attacks the nine basally situated internodes, the second to fourth generation the 10th internode or higher and side shoots induced by stem damage (Tscharntke 1986).

immigr.: USA (eastern). Phragmites australis (Poaceae).