DESCRIPTION: The fresh galls are green and somewhat hirsute whilst older galls are brown and smooth. The general shape is gobular. The chamber is thick-walled and contains a single green inner gall. More often than not several galls are seen to coalesce. The causal agent is a wasp.  DISTRIBUTION: A rare species found in southern Britain.  HABITAT: Found on several species of Oak, particularly Quercus cerris.