Phylloxera perniciosa
Thorny, yellowish-white, and smooth; diameter 2.0–8.0 mm; occurs on petioles, stems, or along midvein of leaves with the underside usually more convex. Opening is elongate and thorn-like.
”- Fredericka Blair Hamilton: (2019) Species Diversity of Hickory-feeding Phylloxerans (Hemiptera: Phylloxeridae) in the U.S.©