Auplopus carbonarius, a nationally notable species, is one of the most interesting of the Pompilidae because uniquely among the British group it constructs a nest of barrel-shaped cells in which spiders are stored and the larvae develop.
About 10mm (male 8mm) in size, the wasps are found from June to August, the male distinguished by the ivory-coloured maculae alongside the eyes. In August 2005 I was lucky enough to see and photograph them mating near a root-plate. Three males effectively lay in wait and when a female appeared they homed in, resulting in a mating frenzy.
After the wasps had careered around the ground for more than two minutes, they separated. The female was evidently exhausted, to such an extent that I was able to place her on my finger and leave her there virtually motionless for more than a minute - very unlike the usual intense activity of Pompilidae. The males had another go when she was put down on the root-plate but this time she got away.
Auplopus carbonarius need water and soil of one sort or another to construct their cells. In keeping with this, the females which nested behind part of the wood in the root-plate were in almost constant motion ferrying small, damp bundles of sand. One had her nest site above a disused spider's web, across which she readily ran to gain entry.
There can be anything up to ten cells in a nest and the prey, a wide range led by Clubionidae, often have their legs amputated to aid carriage. This can be effected by flying, though more often on the ground.
Images © Jeremy Early. All rights reserved.
In 2013 I published My Side of the Fence - the Natural History of a Surrey Garden. Details may be found, and orders placed, via this hyperlink My Side of the Fence. In November 2015 Surrey Wildlife Trust published the atlas Soldierflies, their allies and Conopidae of Surrey, jointly written by David Baldock and me. Details are on this web page: Atlas.