Ectemnius cavifrons

At 11-16.5mm this is one of the largest Ectemnius species. They are very hard to identify from photographs and a specimen is usually required. The males can sometimes be identified from a good view of the nobbly antennae. The females require an even closer view of the verntral plates and clypeus.

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’.

Brownfield, grassland, hedgerows.

June to October. Double brooded in some years.

Nests in tunnels in dead wood where the adults stockpile paralysed Syrphidae in separate cells on which the larvae feed.  Nectars on umbellifers and also takes honeydew.

Widespread across Wales and southern and central England. A scattering of records from Scotland and Northern Ireland.

Common in Leicestershire and Rutland. There were 68 records of this species at the end of 2018.

The fly Macronychia striginervis is an inquiline in the nests of larger Ectemnius species like this.