Phylloxera stellata Duncan
Apterae (BL c. 0.5 mm, colour unrecorded) caused brown spots on undersides of leaves of a Quercus sp., margaretta (= stellata or alba, in mid-August in Texas, USA (Duncan 1922). Other morphs and life cycle are unknown.
”- Roger Blackman, Victor Eastop: (2013) Aphids on the world's plants©
Reference: http://www.aphidsonworldsplants.info/d_APHIDS_P.htm#Phylloxera