The genus Ectemnius contains some of our larger and more colourful aculeates. All ten British species in this genus have black gasters which are boldly marked with yellow transverse bands or paired lateral spots. Most are locally distributed throughout much of southern England, the number of species and their degree of abundance decreasing northwards. Only three species are known from Ireland (Stelfox, 1927) and a similar number from Scotland.

Ectemnius cavifrons is one of the largest and most common species of its genus in Britain.

See Oxybelus uniglumis for general notes on this species.

This is a very close relative of Ammophila sabulosa; in many of its sites it flies with its congener, and may be locally abundant.

This is a conspicuous and relatively large solitary species.

Ecological studies in the Norfolk Brecklands (Field & Foster, 1995; Willmer, 1985a,b) and Europe (Hamm & Richards, 1930) make this one of the best-known British aculeates.

This species is a very close relative of C. ruficornis and care is necessary to distinguish between them, particularly when identifying males.