LOWLAND HEATHLAND - SOLITARY WASPS

Due to the geographical separation of Britain from mainland Europe, we have significantly fewer aculeate Hymenoptera (wasp, bee and ant species), and a number of those are under severe pressure. We have 270 species of Apidae (bees), while the Netherlands has 338. Taking just one group of solitary wasps, the Sphecidae, we have 129 species compared with 292 in France and 168 in the Netherlands. Clearly what we have, we should value and, in the interests of biodiversity, try to protect.

Lowland heathland, especially in Dorset, provides the best opportunity of studying solitary wasps at close quarters, with dozens of species present. Some are dealt with in the sections on Pompilidae and Sandpits in this section - here are a few of the others.

Sphecidae vary in size from about 4mm (Spilomena) to nearly 30mm (Podalonia and Ammophila) and prey on a wide variety of invertebrates, from aphids to honeybees via bugs, beetles and caterpillars.

Lindenius panzeri is one of the smaller species, about 6mm in size, and they are restricted in range. They nest in compacted soil, sand or clay, and prey on small flies. Their mating frenzy involves 'stacking' of males on a female, which is not uncommon among aculeate Hymenoptera. There are more images of Lindenius panzeri on the Sandpits pages. The closely related Lindenius albilabris is commoner with much less colour on the face. They use the same habitat but catch Homopteran bugs as well as flies, as can be seen in the image.

If you'll pardon a mixed metaphor, there is always a fly in the ointment for solitary wasps and for Lindenius albilabris it is Hedychridium coriaceum (5mm), a tiny metallic blue and red parasitic jewel wasp. As so often with parasites, this one is much harder to see than the common host and is in fact a Red Data Book species found in only a few places in the New Forest and on the light soils of the Thames Gravel Terraces around the London area. They are in flight from mid-June to the beginning of August around short, sparse grass in hot, sandy places.

Astata boops, seen from June to August, is a chunky species (12mm) which provisions the nest with shieldbug nymphs (Pentatomidae). These are harder to transport than some invertebrates owing to their depth and width being quite considerable if they are late instars, as the image above shows. The male is seen less often than the female but is conspicuous where he does appear, advertising his presence on a perch to which he keeps returning almost like a dragonfly.

The female digs a 10cm burrow with side branches containing up to 12 cells in friable or compacted sand, which means there can be 40 shieldbug nymphs in each nest, though presumably significantly fewer for the female shown above. Prey is caught some distance from the nest in many instances, perhaps 50 metres or more.

Like Ammophila spp, the wasp covers her nest with a stone or piece of soil when going off hunting, but for some reason, unlike Ammophila, she does not do this every time, which gives the Chrysid wasp Hedychridium roseum (8mm) a chance to get in and do her stuff.

The Hedychridium roseum female above waited for more than ten minutes close to the nest before seizing the chance to enter once the wasp had departed, and was inside for three minutes. Coincidentally - perhaps - the numbers of Astata boops on the site were lower the following year than at any time for at least five years. The following year figures were back to normal.

From the same genus as Asata boops, but sometimes only half the size, and much less common, is Dryudella pinguis. This species is also a heathland specialist on sand, using bare or sparsely vegetated areas to build its 6cm burrows which are filled with Pentatomidae or Lygaeidae bug nymphs.

The pictured female did not cover her nest on leaving to hunt, and had an astoundingly firm grip on the bug, which she did not release even when captured and placed in a small glass tube for definite identification. On release, there was no readjustment, she simply flew off at full speed, returning a couple of minutes later to enter the burrow. Dryudella pinguis males can be distinguished from Astata boops by the white marks on the face.

Completely different prey to provision the nest are taken by Tachysphex pompiliformis (10mm), which uses nymphs of grasshoppers including Chorthippus species. They are active from May to September and the number of nymphs placed in the nest decreases as the year progresses and the grasshopper young develop. This species is probably preyed upon by the small cuckoo wasp Hedychridium ardens (5mm) and a larger and nationally scarce one, Chrysis illigeri (8mm).

Harpactus tumidus (10mm) tends to be seen running rapidly across the margins of heathland rides and paths, and while distinctive in appearance they are certainly difficult to see close up. Not uncommon, they catch leafhoppers to provision the nest. They are parasitised by an elusive and fast-moving cuckoo wasp, Nysson dimidiatus (7mm). These are not easily mistaken for any other species since they have distinct white, red and black markings. Nysson dimidiatus also parasitises Lindenius albilabris, shown above.

A small and fairly common species is Diodontus minutus (5mm), which hunts winged aphids and can catch around 400 of these to stock a multi-celled nest in the sand to feed its larvae. In the breeding season males are often seen swarming in flight close to the ground looking for females.

From the same genus - we have four species in Britain - is Diodontus tristis. This is scarcer, larger at 8mm and entirely black and tends to nest in vertical banks of sand. Even rarer, a Red Data Book species in fact, is Diodontus insidiosus (6mm). This flies from May to August in dry, sandy areas where nests are usually dug in bare or sparsely vegetated banks.

Another scarce species from a different genus that nests in sand is Crossocerus palmipes (7mm), which catches Diptera. The male is particularly interesting in appearance since the forelegs show remarkable dilation on the tibia similar to that shown by Crabro species males including Crabro peltarius.

Closely related to two species shown in the Sandpits pages of this section, namely Cerceris arenaria and Cerceris rybyensis, Cerceris quinquefasciata (11mm) is much rarer and a Red Data Book species as well as the subject of a Biodiversity Action Plan. This female was only the third seen in Surrey in the last century. If is common anywhere, the locations are East Anglia, Essex and Kent, though as with certain other solitary wasps, warmer and longer summers may encourage an expansion in range.

Prey, with anything up to 500 stored in a multi-celled nest, consists of mostly small weevils taken on Gorse though some are larger, as in the image above. This one is Sitona lineatus, found on Fabaceae, and in 2008 a nesting female used Meligethes, or seed, beetles, confirming the wide variety of prey. The nest entrance is pretty small, to the extent that with more sizeable prey access can be consistently a harder job than for Cerceris arenaria or Cerceris rybyensis. The first year's nest was on level, sandy ground, well hidden close to a tree root-plate beneath small twigs and chippings in an open area covered in light tree and shrub 'litter', the result of sensitive clearance of Sycamore (Acer pseudoplatanus) and shading scrub by the landowner, the Borough of Reigate & Banstead.

Unfortunately by definition such a habitat tends to be ephemeral unless it is managed systematically, because undergrowth, led in this instance by bracken and brambles plus shooting Sycamore, swiftly takes over. One year on, a female nested within 30cm of the previous year's burrow, in more open sand, so keeping the area cleared almost certainly proved useful.

Another Cerceris species, Cerceris ruficornis, is the largest of the group at up to 13mm. This one looks very similar to Cerceris arenaria but the female has a distinctive face in so far as the lower part (clypeus) projects forwards rather like a beak. The reason for this is unclear. Cerceris ruficornis catches weevils on heather and is scarce, with the strongholds in Dorset, Surrey and West Sussex from July to September.

Ancistrocerus trifasciatus (12mm), seen from June to September, is one of the potter/mason wasps and reasonably common though still not exactly numerous. It can function in different soil types and different habitats, from gardens to parkland and marshland as well as vegetated heathland.

The species nests in cut plant stems or holes in wood - the pictured female was about to collect soil to create partitions in her nest in a heathland root-plate. Prey consists of larvae of Lepidoptera or Coleoptera.

Two species unique in Britain because they parasitise mature larvae of Scarabaeidae beetles (chafers and/or dung beetles) by burrowing into the ground to lay eggs are Tiphia femorata and Tiphia minuta. The former is larger, at 10mm, and is seen from June to September. Both can be found in various habitats. Larger still is the so-called Velvet Ant, Mutilla europaea (to 15mm), which has a tremendously powerful sting. This nationally scarce species parasitises principally bumblebee nests. The females resemble other 'primitive' wasps such as Myrmosa atra in not having wings and moving very fast across the ground. The males have wings.

Similarly, the Nationally Scarce Methocha articulata is one of the more remarkable solitary wasps. This is partly because the wingless female looks much more like an ant than a wasp (males have wings and are entirely black, as shown above). The synonym Methocha ichneumonides is also revealing about the appearance.

The species can vary enormously in size, from 5mm to 12mm, and preys on tiger beetle larvae. Seen, if one is lucky, usually from June to August running about in sandy areas, once a female finds a prey burrow it allows itself to be grasped by the occupant.

Normally this means death for the insect grasped, but since Methocha articulata's thorax is heavily armoured the Tiger Beetle larva is unable to make any progress in subduing the wasp. Instead, the larva is stung close to the head and soon immobilised before being taken back into the burrow, which is covered up, to provide food for the wasp's progeny.

Members of the Trypoxylon genus are long, black wasps which catch spiders, often Araneidae (orb-web spiders). They are by no means heathland specialists, associated equally with woodland and sometimes homes and gardens too. They tend to nest in twigs, stems (especially bramble) or even thatch, often using tunnels made by other Hymenoptera or Coleoptera.

Trypoxylon species also make use of appropriate burrows in sand banks, and the female Trypoxylon medium on this page - large even by the standards of the species at 16mm - was nesting in an abandoned Odynerus spinipes burrow on a root-plate on the Greensand Ridge in Surrey. She wasn't the only one either, and there was another very similar though usually smaller species, Trypoxylon figulus, also nesting nearby.

Trypoxylon medium and Trypoxylon figulus can construct around half a dozen cells, with an average of ten spiders in each, starting with males and ending with females. There is a fly, or rather wasp, in the ointment though in the shape of the Chrysid wasp Trichrysis cynaea. In June 2007 the female Trypoxylon medium which came under my notice actually flew out and attacked a passing Chrysis viridula (the cleptoparasite of Odynerus spinipes), then five minutes later launched an assault on a Trichrysis cyanea which went into the burrow. The defensive armour plating on the abdomen - necessary if only because, unlike Nomada bees for instance, Chrysid wasps tend to be much smaller than their hosts - served both victims well.

The action was fast and furious, in flight, on the vertical root-plate and falling on to the ground, but despite strenuous efforts to kill them, the Trypoxylon was forced to give up and both Chrysids were able to fly away, though the Chrysis viridula seemed a bit stunned at first.

Miscophus concolor (6mm) is another species that catches spiders but is not one of the Pompilids (spider-hunting wasps). They are small and very active, running, jumping and flying short distances in a manic manner. They also fly straight into their nests in the sand with their prey.

Miscophus concolor are found in July and August mainly on heaths in Dorset, Hampshire, Surrey and West Sussex. There are two rarer species, Miscophus bicolor in East Anglia and Miscophus ater in Kent and Sussex.

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.