Eriosoma (Mimaphidus) pyricola Baker & Davidson

Galls on Ulmus spp. (americana, procera) are clusters of bloated leaf tissue like those of E. lanuginosum (see Alfieri 1920; as inopinatum). The fundatrix and apterous fundatrigeniae are grey, emigrant alatae produced in second and third generations are brown with pale yellow abdomen (cf. lanuginosum); BL 1.3-2.4 mm. Migration occurs in June-July to fibrous rootlets of Pyrus communis or Cydonia. Apterous exules are yellowish pink when immature, pink to red when adult, rather sparsely clothed with filamentous wax (Baker & Davidson 1916); BL 1.3-2.0 mm. Sexuparae are shiny dark green to brown, and return to elm bark in September-October. In southern Europe (Italy, Yugoslavia), Turkey, and introduced into south-east Australia, Tasmania, New Zealand, USA (western and some north-eastern states), Canada (British Columbia), South America (Argentina, Chile) and (probably) South Africa. Swenson (1971) studied the influence of the secondary host on sexupara production. This aphid is often confused with E. lanuginosum in the literature. E. alabastrum Pashchenko (1988), described from U. japonica in Siberia, is very similar and possibly a synonym. It also seems likely that E. dilanuginosum Zhang (1980b), described from U. pumila in China, and with all morphs including the apterous exules on Pyrus now described (Qiao et al. 1999a; and again by Qiao et al. 2001b under the name Siciunguis novena), is this species. If this is so, then a record of E. dilanuginosum from Kazakhstan (Kadyrbekov 2018a) may also be ascribable to E. pyricola.

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

Reference: http://www.aphidsonworldsplants.info/d_APHIDS_E.htm#Eriosoma