Hymenoptera: Cynipidae - gall wasp Isocolus rogenhoferi Galls in bracts of Centaurea scabiosa, Greater Knapweed Host: Centaurea scabiosa Forms a hard, shiny, oval swelling of the base of a bract or an achene. Unilocular, the larva pupating and hibernating in the gall. The large exit holes shown below are probably those of a parasitic Chalcid. The Chalcidoidea database includes a number of Pteromalus associated with Isocolus rogenhoferi

Isocolus rogenhoferi
Holes Bay, Dorset. September 2018