As a group the bees in the sandpit are of more interest than the wasps, in terms of rarity at least. There are at least five Red Data Book species - Andrena florea, Heriades truncorum and its cleptoparasite Stelis breviuscula, and two more cuckoo bees, Nomada fulvicornis and Sphecodes niger.
(Red Data Books were initially published by the Nature Conservancy Council, precursor of English Nature, in the 1980s to "draw attention to the status of the rarest and most threatened animals and plants" in Britain. Category 1 is endangered, category 2 vulnerable, category 3 rare. As an indication of the depth of the problem, 37 species of wasp, bee and ant were included. The books are still the basis of much conservation practice, and are being updated all the time as new information arises.)
On top of that quintet, two 'new' species which are spreading across Britain were seen in 2007, namely the social bee Bombus hypnorum and the solitary mining bee Colletes hederae. My sightings of the latter nesting in one of the sand banks in October were the first in Surrey.
Colletes hederae (to 14mm) is related to Colletes succinctus, shown on the Heathland bees page, and Colletes halophilus, a coastal species. It tends to be larger than the other two and is seen much later because it forages on Ivy (Hedera helix). With little competition for the pollen plant, and no parasites along the lines of the Epeolus bees which attack other Colletes species, the bee is in a position of strength granted the requisite amount of Ivy and warm autumns.
First recognised as a separate species in 1993, when its UK distribution was restricted to the Channel Isles, Colletes hederae was first seen on the mainland in 2001 and is spreading rapidly in what looks an unstoppable and welcome development. They can breed in bulk at appropriate nesting sites, using such habitats as dunes, paths and sand banks, and some sites contain thousands.
Disappointingly there was no sign of any Colletes hederae at the sandpit in 2008 but in September-October 2009 a total of 13 burrows were dug, and further success followed in 2010. That paled by comparison with 2011, when more than 130 nests were completed, and 2012, with more than 200. By 2014 there were around 700, and in 2015 and 2016 the best part of 1,000. With luck the colony is secure but there has been no management for several years and scrub is beginning to take over.
When there is a woodland or hedge margin, as there is with all the brambles in the sandpit, Andrena florea (11mm) can often be found. This pretty species with red on the abdomen uses only White Bryony (Bryonia dioica) for pollen collection. While overall it remains a rare species (Red Data Book 3), found exclusively in Essex, Hampshire including the Isle of Wight, Middlesex, Surrey and West Sussex, it is not uncommon in those counties.
The earliest species each year, and one of several that make use of the Goat Willow/Sallow (Salix caprea) catkins found in the pit, is Andrena clarkella (13mm). Seen sometimes in February but more often in March, this bee is cleptoparasitised by the handsome cuckoo bee Nomada leucophthalma (10mm).
An equally chunky species using the same pollen is Andrena bicolor (12mm), which has two broods each year, using mostly bellflowers for pollen with the summer brood. The picture shows a female and a male in Clustered Bellflower. The smaller Andrena trimmerana (10mm) is another bivoltine species. The nationally scarce Andrena fulvago (10mm) from the same genus is seen slightly later in the year and takes pollen from yellow composites.
The Lasioglossum genus of mining bees is a large one, with 30 species in mainland Britain, some of which are far from easy to differentiate. Some of the males have striking markings. One of the larger species is Lasioglossum leucozonium (10mm) while Lasioglossum minutissimum is about half that size.
Apart from Nomada leucophthalma mentioned above, there are various other cleptoparasites present, two of which prey upon the mining bees just mentioned. Sphecodes ephippius (9mm) is one of the commonest of the genus and is a parasite of Lasioglossum leucozonium among others. Much less common, nationally scarce in fact, is the smallest Sphecodes bee, Sphecodes longulus (6mm), which parasitises Lasioglossum minutissimum. Both these species are seen in the summer.
Nomada fulvicornis (12mm), by contrast, is active in spring as well as summer. As mentioned above, this is a Red Data Book species. They can be found on the coast but also on heathland, using as hosts Andrena tibialis, Andrena bimaculata and Andrena pilipes. All three produce strong colonies but are local; I haven't seen any at the sandpit but presumably one at least must be there. Similarly, Nomada fabriciana, a small species at 7mm, has a long run, with two broods between March and August. Among its prey is Andrena bicolor.
From a different family but still a cuckoo bee, Sphecodes ephippius (9mm) is one of the commonest of the genus. It is a parasite of Lasioglossum leucozonium among others. Much less common, nationally scarce in fact, is the smallest Sphecodes bee, Sphecodes longulus (6mm), which parasitises Lasioglossum minutissimum.
One of the Megachilid bees, the leaf-cutter group who use a brush under the abdomen rather then on the legs to collect pollen, is a specialist of the heaths in Surrey, Hampshire and Kent in particular. This is Heriades truncorum (8mm), a Red Data Book species which appears to be increasing in numbers and range. They are seen from June to September and nest mainly in wood, using beetle holes, or stems. Pollen is collected solely from Asteraceae, mostly Ragwort (Senecio jacobaea), of which there is quite a lot in the sandpit. More details of nesting can be found in the Gardens section of this website.
Heriades truncorum is subject to attention by a rare cuckoo bee, Stelis breviuscula (6mm), which is slightly smaller but similar in appearance apart from lacking the pollen brush. First found here in 1984 in West Sussex, this was provisionally a Red Data Book 1 species but has been found in a number of places since, increasing its range as the host does so. Besides the sandpit, I found them at two other sites within a one-mile radius of Reigate in Surrey in 2007.
Myopa pellucida (8mm) is a fly that acts as a parasitoid of solitary bees. Formerly it was rare and designated Red Data Book 3 but there has been an upsurge in records over the last 15 years. The fly lies in wait on vegetation then launches itself at a bee, laying an egg inside the back. The resulting larva consumes the host then pupates in 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.