Dryocosmus asymmetricus (Hymenoptera: Cynipidae)
Split Twig Gall Wasp
Angelo Coast Range Reserve, Mendocino County, California
April 23, 2008

Wasp-induced stem gall on canyon live oak (Quercus chrysolepis). The stem has split open, enabling the wasps to emerge. Old larval chambers, with holes where the wasps emerged, are visible.