1. Pronotal plate complete, with edges reaching the anterior mesoscutum and forming plate conspicuously raised above rest of pronotum (A) [paired arrows indicate margins of pronotal plate]. Metatarsal claws with conspicuous basal lobes (B). Gall inducers or inquilines on Rosaceae ...Diastrophini

— Pronotal plate incomplete, well-defined only ventrally and with edges not conspicuously reaching anterior mesoscutum (a, b) [paired arrows indicate margins of pronotal plate]. Metatarsal claws simple, without conspicuous lobes (c, d). Gall inducers on other families ...2

2. Pronotum in dorsal view short, with medial height about 1/5 as long as outer lateral margin (A, B). Antennae always 14-segmented in females and 15-segmented in males. Fore wing always with conspicuous areolet (C) and always with marginal cell open (C). Gall inducers on Papaver (Papaveraceae) only. Palearctic only ...Aylacini.

— Pronotum in dorsal view long, with medial height about 1/4 to 1/3 as long as outer lateral margin (a). Antennae 12-, 13-, or 14-segmented in females and 13-, 14-segmented in males. Fore wing with (c) or without areolet (b), and with marginal cell open (b), closed (c), or partially closed (d). Gall inducers on herbs other than Papaver, primarily Asteraceae and Lamiaceae but more rarely on other families (including Papaveraceae). Palearctic or Nearctic ...3

3. Marginal cell partially closed, with vein R1 reaching and continuing along anterior wing margin but terminating long before reaching vein Rs (A, arrow). Pronotal submedial pits shallow and effaced, apparent as a continuous transverse medial impression (B, arrow) ...Phanacidini

— Marginal cell either entirely open without vein R1 conspicuously continuing along wing margin (Fig. 20) or entirely closed (Fig. 21) Pronotal submedial pits deep and apparent as a pair of conspicuous ovate impressions (Figs 25–26, arrows) ...Aulacideini