LOWLAND HEATHLAND - SANDPIT WASPS (Philanthinae: Cerceris spp)

Minus prey, Cerceris rybyensis are elegant fliers The wasps pair on the ground but find cover for mating Cerceris rybyensis catch pollen-bearing bees
Cerceris arenaria male An initial pairing on the sandy slopes of the pit Female Cerceris arenaria in flight with a weevil
A rare case of burrowing after depositing the prey Leaving the burrow to collect the weevil The weevil is grasped, but in this instance not interred

Cerceris rybyensis (12mm) is a widespread digger wasp found from June to September. They prey on various types of mining bee which are usually caught when laden with pollen and returning to the nest. This is by far the most efficient method because unlike the source of pollen, the nest location is fixed, and the bee's load makes its flight slower.

Although various types of bee are taken, there are claims that each Cerceris rybyensis nest, which is up to 15cm long with a number of cells, tends to contain only one species among the 30-40 interred. Like the Beewolf (Philanthus triangulum), the female orientates herself by flying around her nest site every time she goes on a hunting trip. On returning, she flies straight into the burrow at speed with the bee.

When mating, Cerceris rybyensis join on the ground but swiftly fly away to find better cover for the act, in undergrowth, a hedgerow or a tree.

Cerceris arenaria (female 15mm, male 12mm) is one of our commonest digger wasps, sometimes found in large numbers in a fairly small area. They follow the same method as rybyensis in mating and in concentrating on one species to feedThis weevil proved almost too big for the Cerceris arenaria the larvae within the nest, which can contain 50 or more prey items.

They usually fly straight into the nest with their prey, and considering those are weevils, not the most streamlined of creatures, it is quite an achievement to carry one in flight for 50 metres or so then hammer into the burrow at a scarcely believable speed.

There are some exceptions, though. One Cerceris arenaria with a large weevil beneath her in the summer of 2005 had to land some way short of the burrow, and it took several attempts and a few minutes for her to get back into the air.

Another left a weevil nearby while she went to dig a burrow - normally the excavation is effected before hunting starts. On finishing the burrow, she ignored the weevil.

A third had a fight with a female who had brought a weevil to the burrow. The interloper - or more likely the original creator of the burrow, since the species apparently is not averse to occupying existing nests - was seen off and left her weevil on the ground.

The victress was not interested in the weevil - although in the picture on this page she looks as if she is pulling the prey into the nest, for some reason she flew off with it and returned unencumbered, ready to go and find one of her own.

There is a separate page about photographing aculeates in flight on this hyperlink.

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.