Overview
Members of the family (gall wasps) are gall-inducers on oaks, roses and various herbs, or are phytophagous inquilines in galls, mostly of other Hymenoptera. In the northern hemisphere, cynipids are virtually all host plant specific, and can be identified by the unique morphology of their galls. Those associated with oaks (Quercus) have complex sexual and asexual generations. Cynipids that are gall inquilines (tribe Synergini) usually kill the primary host insect at an early stage and subsequently cause modification of the shape of the gall.
The few native Australian species, several of which are undescribed, are possibly inquilines in the galls of various chalcidoids. Across Australasia, many species from various families of Chalcidoidea (eg. Eulophidae, Pteromalidae) occupy the gall-inhabiting niche otherwise filled by Cynipidae in the Holarctic region.
Description
Members of the family are small to medium-sized wasps (1.5 4 mm), with a sculptured mesosoma, and laterally compressed metasoma. Females have the hypopygium (the last visible sternite of the metasoma) produced posteriorly into a small spine and/or have an extremely narrow pronotum, but males are often difficult to identify.
Distribution
This family is very diverse in the northern hemisphere as indicated by the 600+ species that occur in North America. However, the phytophagous Cynipidae are poorly represented in Australia and New Zealand, being known from only six and two described species, respectively, of which at least two are introduced.
Further information about the Cynipidae can be found in Fergusson & Hanson 1995, Richie 1993 and Ronquist 1999.