The rarest of our four Crossocerus species with yellow-marked gasters, and regarded as possibly extinct until its recent re-discovery in Hampshire and discovery in Wales.

A small red and black wasp which is a cleptoparasite of the similar looking Harpactus tumidus (Panzer), occurring in the same sparsely-vegetated sandy areas as its host.

Identification keys and general biology are given in Bristowe (1948), Danks (1971), Spradbery (1973), Richards (1980), Yeo & Corbet (1995) and Archer (2000).

Identification keys and general biology are given in Krombein (1967), Spradbery (1973), Richards (1980), Yeo & Corbet (1995) and Archer (2000).

This large and readily identifiable pompilid would not be easily overlooked and is now probably extinct in mainland Britain. The species is, however, still recorded in the Channel Islands.

Identification keys and general biology are given in Morgan (1984), Gauld & Bolton (1988), Kunz (1989) and Falk (1991).

Identification keys and general biology are given in Malyshev (1968), Iwata (1976), Richards (1980), Gauld & Bolton (1988) and Yeo & Corbet (1995).

This species is outwardly similar to others in the Formica rufa-group and is commonly known as the Scottish wood ant.