Identification keys and hosts are given in Morgan (1984) and Archer (2003). Kunz (1994) treats this species as synonymous with C. ignita. Niehuis (2000) considers C. angustula to be a valid species consisting of two subspecies.

This wasp is an obligate social parasite of V. rufa in Europe and Asia. In North America its host is V. acadica. Called the 'cuckoo wasp', only queens and males are found since workers are not reared. See Spradbery (1973), Archer (1979, 1996b, 1997), Edwards (1980) and Else (1994) for keys and biology.

This species was previously included in the genus Astata.

This is probably not a native British mainland species.

A large, robust species with ivory spots on the gaster. Until recently this was the only member of this worldwide genus to be found in Britain, but the recent discovery of Episyron gallicum (Tournier) has complicated matters. Females are readily distinguished by having four comb spines of the fore tarsus (three in gallicum), but males are very similar and require critical examination.

Identification keys and general biology are given in Malyshev (1968), Richards (1980), Gauld & Bolton (1988), Falk (1991) and Yeo & Corbet (1995).

Identification keys and general biology are given in Richards (1980), Gauld & Bolton (1988) and Yeo & Corbet (1995). Females are wingless, but males are fully-winged.

British specimens of the wingless females have black heads, whereas, in Ireland and the Isle of Man, the females have red heads (Stelfox, 1933;Yarrow, 1954a). All males are winged and have black heads. Identification keys are given by Richards (1980) and Yeo & Corbet (1995).

Previously Methocha ichneumonides (Latreille,1805) Identification keys and general biology are given in Champion & Champion (1914), Richards (1980), Gauld & Bolton (1988) and Yeo & Corbet (1995). Females are wingless, but males are fully winged.