Whether G. gallaediplopappum Fyles (1890) is conspecific with G. gallaeasterellum has long been debated (Busck 1903b, 1939; Fyles 1911a; McDunnough 1959). G gallaediplopappum gall biology, which might help resolve this issue, is thus far unknown. Until adequate information becomes available, apparent differences in forewing scale pattern, female genital structure,
foodplants, and larval behavior seem to warrant the separation of these taxa, and the restriction of G. gallaeasterellum as in the above nomenclatural review (Fyles 1911 a, McDunnough 1959).
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The unresolved G. gallaediplopappum Fyles can be tentatively included here. As discussed earlier, it has been reported from Quebec, Nova Scotia, and Maine galling stems of Aster umbellatus Mill. and Solidago rugosa Ait. (Fyles 1890, 1911a; Procter 1946; McDunnough 1959).

G. gallaediplopappi affects that tall and sturdy plant Diplopappus umbellatus Torrey & Gray.
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G. gallaediplopappi forms its gall a foot or two feet above the ground, and the growth above it is unaffected.
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I have opened dozens of the galls, and never found one lined with silk, nor one with the way of exit closed with a plug.

Our material consisted of a good series of specimens bred by myself on galls collected in a dry area on Aster umbellatus at White Point Beach, Queens County, and other specimens bred at Armdale, Halifax County, by D. Ferguson from galls on the same plant. These were all considered to be typical gallaediplopappi Fyles. They agreed with the rather sketchy original description with the exception of the color of the thorax, stated to be "reddish chocolate," but which in all our bred specimens proved to be white with the patagia edged on their inner sides by narrow dark lines.