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Oak artichoke galls, oak hop galls, larch-cone galls or hop strobile〔(A Nature Observer's Scrapbook )〕 develop as a chemically induced distortion of leaf axillary or terminal buds on pedunculate oak (''Quercus robur'') or sessile oak (''Quercus petraea'') trees, caused by the parthenogenetic gall wasp ''Andricus foecundatrix'' (formerly ''Andricus fecundator''), which lays single eggs within leaf buds using their ovipositor. The larva lives inside a smaller hard casing inside the artichoke and this is released in autumn. The asexual wasp emerges in spring and lays her eggs in the oak catkins. These develop into small oval galls which produce the sexual generation of wasps.〔(Galls on UK Safari )〕〔(The Virtual Filed Guide UK )〕 A yew artichoke gall caused by the fly ''Taxomyia taxi'' also exists, but is unrelated to the oak-borne species. Previous names or synonyms for the species ''A. fecundator'' are ''A. fecundatrix'', ''A. pilosus'', ''A. foecundatrix'' (see below), ''A. gemmarum'', ''A. gemmae'', ''A. gemmaequercus'', ''A. gemmaecinaraeformis'' and ''A. quercusgemmae''. The scientific name is now once again ''Andricus foecundatrix''. ==Galls== Young galls exhibit a tuft of long hairs protruding from the centre of the 'artichoke', the remainder being overlapping scales. The hairs are attached to the more solid gall which is released and drops to the ground from August onwards. After August the 'gall' is still visible, but it is really just the distorted leaf bud after the gall has fallen. A well grown specimen can be 2.0 cm long, dark green or russet, generally developing in June and reaching its full size before autumn. The hairy catkin galls are oval, pointed, unilocular and unilarval structures, 0.3 cm long, changing colour from pale green to brown. The hairs are whitish in appearance.〔 The wasps of the sexual generation are sometimes known by the synonym ''Andricus fecundator'' forma ''pilosus'' (DvL 1982).〔(Gall wasps )〕 The gall wasp which emerges from the gall chamber in Spring will always be an asexual female. But she will proceed to lay eggs on oak catkins, with a preference for ''Q. robur'' over ''Q. petraea'', which develop into 'hairy catkin galls'.〔〔Stubbs, F. B. Edit. (1986) ''Provisional Keys to British Plant Galls''. Pub. British Plant Gall Society. ISBN 0-9511582-0-1. P. 46.〕 The Oak artichoke gall is more common on bush or scrub than tree oaks. 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 foecundatrix」の詳細全文を読む スポンサード リンク
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