A small, black sphecid wasp, formerly placed within the genus Psen. It is one of ten species currently placed within the genus Mimumesa to be found in Europe, and is probably the most widespread of those species.

A small, ground-nesting, red and black solitary wasp. The nomenclature of this species has been the subject of some confusion. Identification keys are given in Yeo & Corbet (1995) (as Psen bicolor); Lomholt (1984) (as Mimesa rufa), and Richards (1980) (as Psen bicolor). Prior to the publication of a paper by Spooner in 1948 the species was referred to as Psen equestris, so care is needed when citing older records of this wasp.

First found in Britain in 1978 by M. Edwards. An important paper on this species is that by Else (1997). See also Dicker (1982). A key to European species groups of the genus Passaloecus is given by Merisuo (1974).

Passaloecus species are small to very small, elongate, black wasps which nest particularly in beetle borings in posts and other cavities, and prey on aphids. The biology of this species is described by Merisuo (1973), and keys to the European species groups of the genus Passaloecus are in Merisuo (1974).

Females of this species are readily confused with Priocnemis pusillus, P. cordivalvata and P. gracilis, although the males are readily distinguishable. Keys to species and general biology are given in Richards & Hamm (1939), Wolf (1972), Day (1988) and Falk (1991).

One of three large species of Priocnemis with plentiful erect hair on the face and propodeum (subgenus Umbripennis). P. perturbator is often found at the flowers of Wood spurge, Euphorbia amygdaloides, in woodlands during May. Identification is given in Day (1988). Many early records for this species may be confused with those for its close relative P. susterai Haupt.

A medium sized, long-cheeked social wasp which is the most common species of the genus Dolichovespula in Britain.

An Holartic species, although probably introduced to North America. It is widely distributed in Europe, but scarcer in the north (Lomholdt 1975-76). A key to European species groups of the genus Passaloecus is given by Merisuo (1974).

Distinguished from other Chrysis species in having four distinct acute teeth on the posterior margin of the third gastral tergum, and the first gastral tergite is blue-black. Identification keys are given in Morgan (1984). Information concerning general biology is given by Kunz (1994).