Andricus aries (Giraud, 1859)
ramshorn gall wasp
Quercus robur, Diemer bos
basal part of the gall
same, with exit hole
Quercus robur, Zeewolde, Harderbos © Hans Jonkman: three pictures to show the variability of the gall: from almost no appendages …
… to bearing short appendages …
… to consist of little more than appendages.
declining galls (early July)
Quercus robur, Zeewolde, Harderbos © Hans Jonkman; very inconspicuous gall (mid-August)
Quercus petraea, pubescens, robur.
Originally a species from southeastern Central Europe, but since the start of the 21th century widespread in NW Europe; first record in the Netherlands by Jan-Willem Wertwijn.
Although it seems that, at least in NW Europe, the species only has an asexual generation, Walker experimentally has shown that fresh females may deposit eggs in axillary buds of Quercus cerris.
Bellido, Ros-Farré, Melika & pujade-villar (2003a), Bellmann (2012a), Buhr (1965a), Chinery (2011a), Hellrigl (2009a, 2012a), Hellrigl & Bodur (2015a), Houard (1908a), Katılmış & Kıyak (2008a), Kemal & Koçak (2010a), Koops (2013a), Kwast (2012a), Melika (2006a), Melika, Csóka & Pujade-Villar (2000a), Redfern & Shirley (2011a), Roskam (2009a), Tomasi (2014a), Walker (2001a), Williams (2010a).