Andricus callidoma (Hartig, 1841)
on Quercus, agamous generation

Quercus robur, Belgium, prov. Namur, Saint-Servais, Asty-Moulin, 5.vi.2009 © Jean-Yves Baugnée

Quercus robur, Mierlo, Wolfsven, 1.ix.2012: the gall has five ribs © Arnold Grosscurt

opened gall
Quercus robur, Dronten, Roggebotsebos, 28-31.viii.2019 © Arnold Grosscurt
this gall has a much longer stalk
… and contains inquilines
gall
Slender, unilocular, fusiform gall, less than a cm in size, on a stalk at least as long as the gall itself. Galls from May till October, mature in August.
hostplants
Fagaceae, monophagous
Quercus petraea, pubescens, robur.
on Quercus, sexuele generation
Quercus robur, Germany, Saarland, Bexbach © Volker Fäßler
another specimen

Quercus robur, Dronten © Arnold Groscurt

detail

Quercus robur, Ackerdijkse Plassen © Ben van As

in this case the catkins have extended normally
gall
The sexual generation forms catkin galls, c. 2 mm long, bearing white hairs that are much longer then the diameter of the gall. Often the galls are partly hidden by the bud scales; often also the catkins don’t extend to their normal length. Often high in the canopy of mature trees. Galls are mature end of May.
host plants
Fagaceae, monophagous
Quercus petraea, pubescens, robur.
synonyms
Andricus cirratus Adler, 1881; A. giraudi Wachtl, 1882.
references
Andersen & Fjellberg (1977a), Béguinot (2002g, 2006b, 2007b), Bellmann (2012a), Blanes-Dalmau, Caballero-López & Pujade-Villar (2017a), Buhr (1965a), Burton, Carbonnelle, Ellis & Schneider (2019a), Cerasa (2015a), Chinery (2011a), Eady & Quinlan (1963a), Groom (2011a), Hellrigl & Bodur (2015a), Houard (1908a), Katılmış & Kıyak (2008a), Kemal & Koçak (2010a), Koops (2013a), Kwast (2012a), Lambinon, Carbonnelle & Claerebout (2015a), Lambinon Schneider & Feitz (2012a), Marković (2014a, 2015a), Melika (2006a), Melika, Csóka & Pujade-Villar (2000a), Nieves-Aldrey (1983a, 2001a), Redfern & Shirley (2011a), Roskam (2009a), Tavares (1905a [“cirrhatus”]), Tomasi (2014a), Wiebes-Rijks (1976a), Williams (2010a).