Cornaphis populi Gillette

Galls on Populus angustifolia are crescent-shaped folds of the leaf-edge, pale or streaked with red. In western USA (Wyoming, Colorado, Utah). Apterae inhabit the same galls as the slate-grey fundatrices, and are straw-yellow with black head and four dark patches on the pronotum, dusted with wax. There is no host alternation; alate sexuparae (BL 2.0-2.3 mm) are produced in the galls in July (Gillette 1913, Palmer 1952).

- Roger Blackman, Victor Eastop: (2013) Aphids on the world's plants^©

Reference: http://www.aphidsonworldsplants.info/d_APHIDS_C.htm#Cornaphis