Coelioxys elongata

This is a darkly coloured bee 11 to 15 mm in length with narrow, sharply defined bands of pale hairs on the abdomen, hairy eyes and a toothed scutellum. As with all species in this genus, the female has a distinctively pointed end to the abdomen, whilst that of the male has several prongs. Female Coelioxys should be treated with care as they may sting; males are said to emit an unpleasant odour when handled.

Where a photo is surrounded by a red box it means that it is representative of the species but may not be the actual species described.

Most solitary bees and wasps are difficult to identify, and can rarely be identified from photos taken in the field.  All red-rated records should include a photo or set of photos of the specimen, illustrating the key characters taken from a standard key, which should also be referenced (e.g. ‘Falk, 2015’).  The full set of key characters are generally not visible in field photos and photos are rarely sharp enough. To aid in the verification of your records, please include face shot, side, top and wings.  The notes should state whether male or female, and explain how the specimen met the key characters.  Although NS may not be able to identify the species even if these reference photos are provided, the photos will be stored with the record and may allow it be identified in future.   Alternatively, NS will accept records identified by a recognised local or national expert, or that have been identified via BWARS’ Facebook https://www.facebook.com/profile.php?id=100065021433202 .  If you have obtained this advice, please note the name of the person/organisation identifying the record in the ‘determiner’ field (e.g. ‘Stuart Roberts, BWARS Facebook’) rather than just a comment of ‘BWARS Facebook’.

Where the host species nests are to be found.

June to August.

This species is a cuckoo bee, acting as a cleptoparasite of Megachile willughbiella and M. circumcincta. Female Megachile bees construct nests of larval cells from leaves and provision each cell with a mixture of pollen and nectar for the young. Female Coelioxys bees seek out these nests and use their sharp abdomens to pierce the cells and lay an egg. This egg hatches before that of the Megachile bee and the second instar larva uses its long curved jaws to crush the egg or young larva of the Megachile host. The Coelioxys larva can then feed on the contents of the cell, having normal jaws in its later instars. It pupates within a cocoon spun within the host cell where the larva overwinters as a prepupa before emerging the following summer.

Widespread but local. Found throughout mainland Britain from Cornwall to the Highlands in Scotland. It does appear to have a southerly and coastal bias with an apparent absence from the English Midlands, East Anglia and inland Scotland and Wales.

Scarce.