Eriophyes pyri (Pagenstecher, 1857)
pearleaf blister mite
on Pyrus
Pyrus spec., Hungary, Budapest, arboretum, 18.iv.2018 © László Érsek
the “pocks” are hollow
31.iii.2017: the galls are already present in the yet unopened leaf
28.vii.2017: in summer the galls turn brown

Pyrus communis, Roemenië, Bucharest; from Cean, Cean & Stǎnicǎ (2012a)

another aspect
Pyrus communis, Dronten, 29.iv.2010 © Arnold Grosscurt

Sorbus aucuparia, Castricum

Sorbus aucuparia, Nunspeet, huize De Vennen: bovenzijde

the underside has an inconspicuous opening

tranverse section: the gall is loosely filled with a loose spongy parenchyma.
detail

Sorbus aucuparia, Huijbergen, Staartsche Duinen: old galls turn dry, becoming brown pocks

Sorbus aria, France, dépt. Lozère, Florac © Sébastien Carbonnelle: old galls
Sorbus torminalis, France, dép. Dordogne, Le Breuil, 2.v.2019 © Arnold Grosscurt
gall
the mites do not live on the leaf surface, but within the abnormally loose sponge parenchyma; they hibernate in the buds.
host plants
Rosaceae, oligophagous
Amelanchier ovalis; Cotoneaster dammeri, integerrimus, nummularius, tomentosus; Cydonia oblonga; ? Malus domestica; Mespilus germanica; Pyrus communis & subsp. pyraster, nivalis, regelii,, spinosa; Sorbus aria, aucuparia, chamaemespilus, domestica, graeca, intermedia, obtusifolia, rupicola, torminalis.
That the species would live also on Ribes odoratum (Roskam) is a mistake.
synonym
Epitrimerus, Eriophyes, Phytoptus pyri; Eriophyes, Phytoptus, sorbi (Canestrini, 1890); Eriophyes variolatus Nalepa, 1892; E. pyri var. variolata.
references
Abras, Fassotte, Chandelier & Cavelier (2008a); Béguinot (2002a,e,f,g,h, 2003a,b, 2006a, 2007a,b, 2012a), Bellmann (2012a), Bohinc & Trdan (2013a), Buhr (1964b, 1965a), Cean, Cean & Stǎnicǎ (2012a), Chinery (2011a), Cogolludo (1921a), Coulianos & Holmåsen (1991a), Dauphin & Aniotsbehere (1997a), Denizhan, Monfreda, de Lillo & Çobanoğlu (2015a), Farkas (1965a), Fjelddalen (1995a), Geçer & Denizhan (2015a), Hellrigl (2003a), Houard (1908a [“piri”]), Jočić & Petanović (2012a), Kapaxidi (2013a), Keifer, Baker, Kono, Delfinado & Styer (1982a), Kołątaj (2019a), Koops (2013a), Lambinon, Carbonnelle & Claerebout (2015a), Lambinon, Schneider & Feitz (2001a), Lehmann & Flügel (2012a), Lehmann & Hannover (2016a), Lotfollahi, Irani-Nejad & de Lillo (2014b), Mifsud, Monfreda & de Lillo (2007a), Petanović & Stanković (1999a), Redfern & Shirley (2011a), Ripka (2008a, 2020a), Roivainen (1947a), Roskam (2009a), Schliesske (1988a), Skoracka, Lewandowski & Boczek (2005a), Stănescu (2009a), Sylvén (1960a), Tavares (1905a), Tomasi (2003a, 2012a, 2014a), Vaněčková-Skuhravá (1996a), Weidner (1954a), Xue, Sadeghi & Hong (2009a).