Length 10 to 20 mm. A fairly large cuckoo bee. Queens have two yellow bands on the thorax, abdomen all black with greenish-yellow tip with extensive side patches, males are similar but with more extensive greenish-yellow areas on the abdomen.

All red-rated records should include a photo, or set of photos, showing the key characters, which may require the specimen. Please include a face shot, side, top and wings.  Note whether male or female, explain how the specimen met the key characters and the key used.  We will accept records identified by a recognised local or national expert, or that have been identified via the BWARS’ Facebook noting the name of the person/organisation identifying the record (e.g. ‘Stuart Roberts, BWARS Facebook’).

Found nectaring in gardens, hedgerows and flower meadows.

April to September. Queens emerge in April and May, males and new queens in July and August.

Parasitic in the nests of Bombus pascuorum.

Widespread but not particularly frequent in Britain.

Occasional in Leicestershire and Rutland.