Phylloxera rileyi Riley

Apterae are dark brown with dorsal tubercles almost black (but paler forms mat occur); BL c. 0.6 mm. On undersides of leaves of Quercus alba and Q. obtusiloba (= stellata) in Missouri, causing white or yellow circular spots. Apparently there is no host alternation; alatae are produced from late July to October, and those of later generations are presumably sexuparae, because sexuales are recorded laying overwintering eggs on twigs (Riley 1875, Pergande 1904, Duncan 1922).

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

Reference: http://www.aphidsonworldsplants.info/d_APHIDS_P.htm#Phylloxera