Phytoptus sp. [tentatively assigned to A tetanothrix]
Willow, Mass. May. Elevated, irregular masses," single or compound; on upper side of leaf and more rarely below. Both positions on same leaf. Green or red according to host willow.
”- MT Thompson: (1915) An illustrated catalogue of American insect galls©
Reference: https://www.biodiversitylibrary.org/page/33339925#page/69/mode/1up