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''Andricus quercuscalicis'' is a gall wasp species inducing knopper galls. Knopper galls develop as a chemically induced distortion of growing acorns on pedunculate oak (''Quercus robur'' L.) trees, caused by gall wasps, which lay eggs in buds with their ovipositor. The gall thus produced can greatly reduce the fecundity of the oak host, making this gall potentially more of a threat to the reproductive ability of the tree than those that develop on leaves, buds, stems, etc. The Turkey Oak (''Quercus cerris'' L.), introduced into Britain in 1735, is required for the completion of the life cycle of the gall.〔( Turkey oak introduction & gall distribution )〕 The knopper is a recent introduction to the British Isles, first arriving in the 1960s and now found throughout England, Wales and as far north as Scotland; first occurring for example in 2007 at Eglinton Country Park in North Ayrshire. == The physical appearance of the gall== The large 2 cm gall growth appears as a mass of green to yellowish-green, ridged, and at first sticky plant tissue on the bud of the oak, that breaks out as the gall between the cup and the acorn. If only a few grubs are developing within, then it may appear only as a group of bland folds. Where several grubs are competing for space the shape may become much more contorted, with several tightly bunched galls.〔(Growth details. )〕 The word knopper derives from the German word 'Knoppe', meaning a kind of felt cap or helmet worn during the 17th century;〔Tait, Norman & Pearl. ''The Spread of Knopper Gall Wasps into the Clyde area''. Glasgow Naturalist 2004, Vol. 24, Pp. 131 - 132.〕 also a small rounded protuberance, often decorative, such as a stud, a tassel or a knob.〔(The origin of the name. )〕 Although normally distinctive the knopper gall can, under some growth conditions, be mistaken for the acorn cup gall, caused by the gall wasp ''Andricus grossulariae''.〔(Acorn Cup gall. )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Andricus quercuscalicis」の詳細全文を読む スポンサード リンク
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