There are 22 types of potter and mason wasps in the UK, all of which are predatory and build their nests with soil, usually clay but sometimes sand. To be scientific, they are Vespidae, not Sphecidae, and come from the subfamily Eumeninae.
One of the commonest is Odynerus spinipes (14mm), a mason wasp which digs a burrow in banks then extends this above the surface with what is assumed to a protective chimney up to 40mm in length. Initially the chimney is made of the excavated soil duly moistened. Water has to be ferried for this purpose. As regards protection, the chimneys are not sufficiently robust to withstand heavy rain, particularly on south-facing slopes, so their validity is dubious.
The female lays an egg in each cell, suspended from the wall by a fine filament, before catching up to 30 weevil larvae of the genus Hyperba (Curculionidae) on which the wasp larva can feed. Each nest has five or six cells, so that's a lot of weevil larvae, especially as in appropriate locations there can be numerous nests.
Once the nursery has been stocked, the chimney (if it is still there) is removed and the nest filled in. However, Chrysis viridula (7mm), a particularly handsome cuckoo wasp which cleptoparasitises only Odynerus species, attempts to profit from the mason wasp's work by entering the nest and laying her eggs to usurp those of the host.
The pictured Chrysis viridula was one of several traipsing along the nesting bank checking out burrows head first then entering rear first to lay. I saw three pairings but as they lasted only six seconds effective photography proved out of the question.
From the same genus as Odynerus spinipes, and catching mostly weevils but also occasionally lepidopterous caterpillars as prey, is Odynerus melanocephalus (11mm). The species is worth showing here even though it nests principally in clay rather than sand and is definitely not in the sandpit. The markings are pale yellow and the nest is constructed in flat earth more often than on a slope or vertical face, while the chimney is always much shorter and sometimes non-existent. A Chrysid wasp which is closely associated with Odynerus melanocephalus is Pseudospinolia neglecta (6mm). Both wasps are scarce and Odynerus melanocephalus was added to the list of Biodiversity Action Plan priority species in 2007.
Gorytes laticinctus (12mm) is a Red Data Book species with striking markings, especially on the face, which has much more yellow than most solitary wasps. Until about 2003 this rare wasp was restricted to two separate parts of southern England: a western area around Dorset and the New Forest and an eastern area in East Anglia and east Kent.
Since then, inexplicably, Gorytes laticinctus has expanded its range and there have now been a number of records from localities between these two areas, mostly in Surrey but also in Berkshire and North Hampshire. Closely related to Lestiphorus bicinctus, which also breeds at the sandpit, they fly in July and August, and occasionally in September, and females excavate nest burrows in the ground, provisioning the cells with various homopteran bugs such as froghoppers.
The Pemphredoninae clan includes Mimesa equestris, Mimesa lutaria and Mimesa bruxellensis (all 10mm), which are found from June to October. The first two are pretty common but Mimesa bruxellensis, which has significantly longer antennae, is nationally scarce.
They dig lengthy tunnels in the sand relative to their size, up to 50cm, in which small homopteran bugs from the family Cicadellidae (leafhoppers) are placed. Prey can be of a fair size. These species can fall victim to the ruby-tail wasp Elampus panzeri (7mm), the only one of the family with a flange at the base of the thorax.
Two scarce species found in 2008 are both more often found on clay soils in Britain, though not abroad. For what it's worth, the sandpit has clay soil just to the south but the suggestion is that the two species were both nesting on the sand. Didineis lunicornis (9mm), which resembles an ichneumon wasp, catches Homopteran bugs (leafhoppers) and is from the Nyssoninae family. It is a late species seen from July to October.
Priocnemis cordivalvata (8mm), a strict spider-hunting wasp or Pompilid with red on the legs, was the second scarce species to turn up. Another subfamily that catches spiders is Larrinae, including the Trypoxylon genus. Trypoxylon medium (maximum 16mm) is one of the largest, and while most of the genus nest in plant stems or beetle borings in wood this particular one had its nest in a vertical bank.
The equally common Chrysid wasp Trichrysis cyanea (6mm) cleptoparasitises Trypoxylon and various other solitary wasp species including the spider-hunting Dipogon variegatus. Although in the so-called ruby-tail wasp group this species, like several others, has no red on it. Check out the Solitary Wasps page in main Heathland section for more about this cuckoo wasp and Trypoxylon medium.
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.