A species closely related to Passaloecus insignis, from which it is separable only with difficulty.

Probably the most common British species of Passaloecus, at least in the south.

In the older literature this species has been placed in the genus Notozus, where it was known as scutellaris or constrictus. Identification keys and general biology are given in Morgan (1984) and Kunz (1994).

Identification keys and general biology are given in Krombein (1967), Morgan (1984) and Kunz (1994). Great care must be taken when distinguishing this species from O. puncticollis.

An all-black species with bifasciate wings. Identification is not too difficult using Day (1988), but it should be noted that the captions to figures 40 and 42 are transposed. The generic name refers to the tufts of forward-pointing bristles on the maxilla of the female; these are used to pack the nest entrance with old spider silk.

Gayubo & Felton (2000) provide an identification key to the six European Nitela species, as well as detailed descriptions. Felton (1987) keyed the two British species, misidentifying N. lucens as N. spinolae.

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.