The asexual generation of Plagiotrochus burnayi, one small wasp of cynipidae family, turns acorns of green oaks to galls. The acorn grows into its dome whilst the tip twists. The insect exits the gall between February and March.
Likely the biological cycle of Plagiotrochus burnayi is heterogonic. However, its bisexual generation is not known.
The genus Plagiotrochus is specialist in causing galls in green oaks and kermes; see also P. quercusilicis.
[photo Xavier Adot]