Hunting for bees at Farnham

Yesterday was a bit of a treat, a day out surveying for bees with Rosie at the RSPB reserve at Farnham Heath. It's one of the premier sites in the country for aculeate hymenoptera (bees, non-parasitic wasps and ants) with a list of well over 200 species. Our aims for the day were twofold. Firstly we wanted see how many species we could find, and to see how this compared to a previous survey in 2002 which was conducted around the same time of year, but when a lot of the site was still under conifer plantation. Secondly we wanted to see if we could refind the extremely rare Lasioglossum sexstrigatum, which has still only been found in a handful of sites in the UK since arriving in 2008.

We failed on the latter, but we're optimistic that by the time all the specimens have been identified we'll have amassed a list that will show the benefits of restoring the heathland. Aided by local experts Tom and David we immediately started finding species I'd never seen (or in some cases heard of) before. Some felled trees near the entrance to the reserve provided the first interest of the day, their upturned root plates providing a vertical profile like a miniature cliff, perfect for nesting bees like the tiny Lasioglossum parvulum. Where you find nesting bees, you often find their parasites, and in this case they outnumbered their hosts, with a small swarm of the smallest Nomad bee in the UK, Nomada sheppardana, loitering around the nest holes.

The diminutive Lasioglossum parvulum

Its equally tiny cuckoo bee Nomada sheppardana

Moving further into the reserve we were sound being treated to a masterclass in bee identification, as Tom and David demonstrated some impressive field knowledge in putting names to a range of Lasioglossum species which look almost identical at first sight. Final identifications will come from examination under the microscope, but we probably added L.morio, L.smeathmanellum, L.leucozonium and L.prasinum to the day list in a matter of minutes.

Lasioglossum leucozonium, refueling shortly after being released

After that the new species continued thick and fast, heading up a sandy track to the accompaniment of Woodlarks singing and a Red Kite swooping past, before stopping at a patch of bilberry where we added a few bumblebee species, including the heathland specialist Bombus jonellus, I finally found my first hoverfly for the day with my first Volucella pellucens of the year, before that was well and truly trumped by Tom presenting me with a Seriocomyia silentis in a tube - a hoverfly that I've been wanting (and failing) to see for ages. After than my first Gorse Shieldbug for a couple of years was a bit over-shadowed!

Gorse Shieldbug

Heading downhill again, we found a few more flowers growing by the side of the track, and with them a new set of bees, including the dazzlingly blue Ceratina cyanea, followed by a lovely female Andrea labiata, with its black tipped red abdomen making it look like a giant version of the many Sphecodes cuckoo bees that were patrolling the heath. Tom also found another cracking non-bee with the spectacular long-horned beetle Rhagium bifasciatum.

Rhagium bifasciatum

After a bit more wandering we ended up at our final site for the day, a large flowering holly that was attracting a range of bees and other insects, including a slightly battered Green Hairstreak and one of the better wasp mimicking hoverflies, Xanthogramma pedissequum.

Green Hairstreak that's been in the wars

Xanthogramma pedissequum

We're hoping to make a return trip in July to see an even wider range of species, and to hunt for the enigmatic Chrysotoxum octomaculatum, one of the rarest hoverflies in the UK, found only on heathland in Surrey and Dorset (where I also have some adventures planned :) )

More hanging around sallows

After a nice long Easter break it was back to work yesterday and today, but that came with the consolation of being able to check out the sallow on the heath, which has come nicely into flower. I was hoping for another new hoverfly, perhaps a Cheilosia grossa, but the only hoverflies to be seen were a solitary Parasyrphus punctulatus and a Melanostoma scalare, both common spring species.

Melanostoma scalare

There were a few more bees buzzing around, possibly more able to fly in the chilly air with their furry coats, including a lovely female Andrena praecox, the small sallow bee. As the name suggests this is a specialist on sallows, the females will only collect pollen from this one tree, they are oligolectic to use the technical term.

Andrena praecox - a nicely distinctive bee

On Thursday there was also a larger Andrena on a catkin, which I think might be a female A.bimaculata. I've not seen it before, and I briefly dismissed it as another honey bee, before thankfully deciding to give it a second look. They look very similar to a number of other Andrena species though, and I'm not quite sure that it's not an Andrena trimmerana, unfortunately I don't think the key characteristics are visible in my photos. In an attempt to clinch an ID I went back to the sallow today with Rosie, armed with our nets, but there weren't any female bees around to catch. We did bag a couple of male Andrenas though, which might fortuitously be one each of bimaculata and trimmerana, we'll take a look under a microscope to check. (Edit - I've now had the ID of the female confirmed as bimaculata, and the males were indeed one of each - very efficient netting!)

Andrena bimaculata

Elsewhere on the heath things are pretty quiet, as there aren't many other sources of nectar or pollen around. The fences did attract a good number of basking flies, including a single Eudasyphora cyanella, a species I'd never heard of before this year before seeing some photos on the UK Diptera facebook group. Once you know to look for the black and white markings at the top of the thorax, they're actually quite distinctive.

Eudasyphora cyanella

The gardens are buzzing with bumblebees, including the first Red-tails I've seen this year, and on a daisy a single dimunitive male Andrena bicolor was taking a rest. These are one of the easier male Andrenas to identify, with the combination of their small size, spindly build and black hairs on the face making them quite distinctive.

Andrena bicolor