Description and notes A medium-sized red and black spider wasp. Identification may be made from Day (1988). The male has a relatively distinct genital plate, but females are very similar to others in the subgenus Ammosphex Wilcke, and considerable care is necessary in identification.

Identification key and general biology are given in Morgan (1984). The only entirely metallic blue wasp in Britain.

Identification key and general biology are given in Morgan (1984). Previously this species was misidentified as H. amoenula and is also known as H. generosa (Förster, 1853) in Kunz (1994).

There are approximately 100 species in this genus worldwide. Lomholdt (1984) states that there are only seven species in Europe, but Bitsch et al. (2001) list ten, although one of these, P. hidalgo, was only described in 1990.Three species have been recorded in Britain.

Identification key and general biology are given in Morgan (1984). Kunz (1994) considers C. bicolor and C. illigeri (Wesmael 1839) to be the same species. Morgan (1984), however, separates these two names.

A small, stem nesting solitary wasp. Identification keys are given in Yeo & Corbet (1995), Richards (1980) and Lomholdt (1984).

A small, black solitary wasp. Identification keys are given in Yeo & Corbet (1995), Lomholdt (1984) and Richards (1980).

A medium-sized red and black species, amongst the largest in its genus in Britain.This species, along with Arachnospila minutula, belongs to the subgenus Anoplochares, characterised by the female lacking a tarsal comb.The male has a characteristic genital plate.

Identification keys are given in Morgan (1984). General biology is given in Morgan (1984) and Falk (1991). The latter treats this species as a variety of C. ignita. However, C. ruddii is readily recognised by the small punctures on the second gastral tergite, relative to those on the first tergum, which are of uniform size and dispersion except at the rear of the tergum.