Posted on 6 June 201820 May 2018 by David Currant gall on oak catkins and leaves Currant galls on oak catkins and leaves. Created when spangle gall wasps (Neuroterus quercusbaccarum)lay their eggs in the catkins or the undersides of leaves of oak trees. Post navigationPrevious post: Comma butterflies at restNext post: Tortoiseshell butterfly feeding, dandelion