LOWLAND HEATHLAND - BEES

Mining bees which gather pollen and place it in a burrow for their larvae to feed on present a bewildering complexity of species, with Apidae, Andrenidae, Halictidae and various Nomada and Sphecodes parasites all battling away in different habitats. Heathland hosts a good number, several of them rare, and their behaviour is fascinating. More are shown in the Sandpits section here.

Pride of place among the rarities goes to Andrena ferox (10mm), which is a Red Data Book 1 species. Uncommon throughout its range, this bee has been recorded in only a handful of places in the south of England and the only regular, reliable location is Denny Wood in the New Forest in Hampshire. Even there the best-known nest seems to be under pressure but it has to be remembered that nests of the species are rarely obvious in the ground and pollen is collected from Oak trees. This makes recording individuals in action none too easy.

One bumblebee which occupies a wide variety of habitats but is particularly associated with heathland is Bombus jonellus (15mm). The queens are among the first seen in the spring, when Sallow is ised for pollen, and nests are fairly small, with fewer than 100 workers. In summer Heather is the plant on which one is likeliest to see them.

Most mining bees nest in strictly solitary fashion but some are communal including Panurgus calcaratus (7mm). They are seen in July and August, and tend to go on Dandelions and Hawkweeds to gather pollen, with several sometimes seen on one flower head. Others, such as Andrena ferox and Andrena bucephala, have several females using one entrance hole into a burrow though they have separate nests within. The much larger Panurgus banksianus (12mm) also does this on occasions but tends to be more solitary. Like Panurgus calcaratus, the species is at home in hard-packed sand.

Male mining bees are often quite different in markings from the females. The luxuriant hair on the clypeus of the male Andrena barbilabris (10mm), which makes him look like some sort of invertebrate Ben Turpin, sets him apart from the female, who can dig her burrow in very compacted soil, invariably in a sandy location.

Andrena tibialis (12mm) is large and very attractive but is quite localised. Typically it flies from mid March to late May using a range of habitats including quarries and sandpits as well as heathland. Andrena bimaculata (10mm), which favours Gorse (Ulex spp) for collecting pollen in the spring (they also have a summer brood) is nationally scarce.The experts tell us that Andrena wilkella is found on grassland and clay soil. Bees do not read books though and the pictured female was seen with several others on a sandy west Surrey heath with no clay content.

In contrast, Andrena flavipes (11mm) is much commoner in sandy localities but is also seen in clay-based areas from March to May and July to September. They nest, sometimes in large numbers, in bare areas of ground exposed to the sun, collecting pollen from plants with short corollae. Together with its cleptoparasite Nomada fucata (9mm), Andrena flavipes has increased in range since 1970. (A cleptoparasite relies on the food stored by the host species for its progeny, a parasite feeds only on the adult or the progeny.)

Like a number of the Nomada clan, which are focussed on more closely on a separate page in the Woodland and Hedgerow section here, the colouring of Nomada fucata might encourage the false belief that it's a wasp. The pictured bee was followed along a 70-metre stretch of open sandy ground, checking out burrows.

Quite how these and other parasites or cleptoparasites ascertain exactly which burrows to hit isn't entirely clear, but presumably they rely on scent, and this one eventually located what she wanted then settled down 10cm away to wait for an opportunity to enter.

When the bee left to gather pollen eight minutes later, the Nomada fucata immediately flew into the burrow and spent four minutes inside egg-laying - unlike some species, these are not smash-and-grab merchants. Her work done, she departed to find another burrow to infiltrate.

Andrena nigreoaenea is large (14mm), with orange pollen hairs on the hind tibia of females, is common throughout most of Britain on various soil types including heathland. They fly from late March to the end of May or June and forage from a large variety of flowers. Nomada goodeniana is the cleptoparasite of this bee. Andrena bicolor (12mm), a common species with two broods, is also shown in the Sandpits pages of this website but is included here to show the remarkable difference in size between male and female.

Two scarce species of mining bee found on heathland are Halictus confusus and Lasioglossum prasinum. Halictus confusus, (10mm), a Red Data Book species restricted to the sandy heaths of south-east England, is very similar, especially in the female, to the common and widespread Halictus tumulorum. They are seen in the summer, as is Lasioglossum prasinum (10mm), a distinctive bee that is very localised in southern Britain, being almost entirely resricted to the lowland heaths of Surrey and Hampshire. The female has a very long flight period for a solitary species, from May to October, and forages mainly from heather. From the same genus, but much smaller, is Lasioglossum parvulum (7mm). Found in varied habitats including heathland, they forage from a range of plants and fly from March to September.

Hylaeus incongruus (9mm) is another Red Data Book species associated with heathland. It has always been restricted to the south-central and south-east counties of England and is usually found at woodland edges, where it nests in beetle and other holes in dead wood.

Nomada rufipes (11mm), one of the handsomest of the Nomada genus, is pretty common where its hosts from the Andrena denticulata group are found, mainly in Heather-clad heathland. Another double act of host and cleptoparasite is that between Andrena humilis (11mm) and Nomada integra. Andrena humilis has declined significantly inland in the last 100 years and is now scarce but can be found occasionally in large aggregations on hard sand or stiff soil. Pollen is gathered exclusively from yellow composites including Hawkweeds (Hieracium spp) and Hawksbeards (Crepis spp). Nomada integra (8mm) is not that common and bears a similarity to several other red and black Nomada species.

Andrena argentata (8mm) and Nomada baccata (7mm) are a couple of other scarce heath specialists. In recent years Andrena argentata have nested in considerable aggregations at Thursley National Nature Reserve in Surrey, displaying the familiar mating frenzy associated with certain hymenoptera where males can be stacked three high on a female. It remains to be seen what effect the severe fire at the site in 2006 had. Nomada baccata lurk around the nesting sites in small numbers biding their time. The males have bolder markings than the females, especially on the face.

Besides the Nomada baccata, the Andrena argentata at Thursley face another problem - the digger wasp Cerceris rybyensis (12mm), which seizes significant quantitites of bees to provision its own nest. On one occasion, though, the biter was bitten when an Andrena argentata male jumped on the wasp's neck and put the latter off its attack. In all probability this was not a deliberate assault but merely an example of a male bee in breeding mode jumping on to the back of the next thing that came into view regardless of genus. Cerceris rybyensis is covered in more detail in the Sandpits pages at the end of this section.

Although Nomada bees are the commonest cleptoparasites with 28 species, there are 16 of another genus, Sphecodes, which are much harder to distinguish in the field and include several scarce ones. Sphecodes crassus (9mm) and the much smaller Sphecodes geoffrellus (5mm), the latter a parasite of Lasioglossum parvulum, are two of the commoner species. Whereas most cuckoo bees leave it to the larva to destroy the host's egg or young, a Sphecodes female does it herself by eating the egg before laying her own. Usually they enter an open nest but the bee shown above spent more than half an hour digging into a sealed burrow to do her work. One of the rarer species, though perhaps a little less scarce now than its national status suggests, is Sphecodes reticulatus (9mm), which is found on many heaths and parasitises Lasioglossum prasinum.

As this analysis suggests, Sphecodes bees tend to cleptoparasitise Halictinae bees. An exception to this rule, Sphecodes rubicundus, is shown on the Woodland bees page. Another smaller group of cuckoo bees, Epeolus, cleptoparasitise mining bees from the Colletes group. One of these, Epeolus variegatus, is pictured in the Purbeck section of the website. The other, Epeolus cruciger, is very similar in appearance though smaller at 7mm and with the female having entirely red legs.

Epeolus cruciger is also less widespread than its relative though still reasonably common on inland heathland and particularly in Dorset. The species deals with just two types of bee, Colletes succinctus and Colletes marginatus, and can be seen from late June through to September.

Colletes succinctus (10mm) is one of ten in the genus in Britain and among the commonest as well as arguably being the most attractive. They can fly in duller conditions than most bees and are found across the country on coasts, inland heaths and moors, virtually wherever Heather is located in fact. The latter is their source of pollen, although in places they visit Asteraceae.

Nesting by Colletes succinctus can be in massive aggregations, with one site in North Yorkshire boasting up to 80,000 burrows in a 100-metre stretch. The pictured bee was one of at least half a dozen females collecting pollen in a smallish patch of heather (12 square metres) in a garden on the Greensand Ridge in Surrey, with no other heather located within a radius of 1,500 metres. Confirmation, perhaps, that if an appropriate plant is found in suitable habitat, bees will be able to profit from it however seemingly remote it is.

The closely related Colletes hederae turned up 100 metres away from the garden where the Colletes succinctus foraged in 2007. There is more information on this newcomer, for which this was the first Surrey sighting, on the Sandpits page.

From the same genus is Colletes similis (10mm), which is widespread in southern Britain and Ireland but never numerous. This is one of the early species, being on the wing from mid-June, and is not restricted to sandy localities though often found there.

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.