Some Solitary Bee "Firsts"

30th July 2012
With the continuing reasonably warm weather, insect activity in the garden has definitely been increasing. I've been really pleased (well excited really!) with opportunities to get images of some solitary bees that I have never seen before or for which I have never managed decent photographs.

It was watching a Leaf-cutter Bee a few years ago, that really got me interested in our solitary bees and determined to learn more about them and to record species that occur locally. Leaf-cutters generally start appearing in June or July. I saw a male on the 13th July and I've now started seeing females in the garden. Leaf-cutter Bees are members of the Megachilidae; a bee Family where the females (apart from the cleptoparasitic species), have their pollen-collecting hairs (the scopa) on the underside of the abdomen. The colouration of the scopal hairs is one of the factors used to differentiate the Megachile species, and the all-orange hairs on this female is consistent with Megachile centuncularis. Identification from photographs is always difficult though (particularly for the non-expert like me!).

This one is cutting a piece of Fuchsia leaf. They typically remove a circular or more elongated section from the edge of the leaf; flying back to the nest with it rolled underneath and held with the legs a mouthparts. The pieces of leaf are used to line the nest burrow and to construct the divisions between the brood cells. They are very industrious and helpfully (for observers/photographers), keep returning to the same plant. They take just a few seconds to remove a "cutting" once they have selected a suitable leaf.

I have some Osmia leaiana Mason Bees using my "Bee Hotel" (the Osmia bicornis (=O. rufa) Red Mason Bees having finished). I've managed a few rather poor photographs of the females, but haven't managed any of the males. I saw this little (around 7mm) bee feeding on Lobelia flowers and had no idea what is was. Looking at the photographs, I noticed the lovely bronzey iridescence and this together with the 13 antennal segments (females have 12), told me that this was a male "something".

After reading through David Baldock's excellent "Bees of Surrey" and trawling various web resources, I decided that this must be a male Osmia, either Osmia caerulescens or Osmia leaiana. They are very difficult to tell apart. Whatever, this is a really attractive little bee and another "first" on my list!

It might be difficult for some, to understand the level of excitement I felt when I saw this bee. I'm surprised myself! Again, this was on Lobelia flowers and I recognised it instantly as one of the Coelioxys species. These are cleptoparasitic bees that invade the nests of Megachile and Anthophora bees to lay their eggs. The developing larve kill the host-bee larvae and eat the food stores. Again, it was constant reference to Baldock's "Bees of Surrey" (which has excellent photographs), that helped me recognise this bee. David Baldock's book is an excellent resource (you don't have to live is Surrey!) and one of the few comprehensive works on bees that is usable by non-entomologists.

The white-banded and pointed abdomen is typical for a female Coelioyxs and I also know that these are elusive bees that are seldom seen. I ran in for my camera and returned to see the bee fly up onto the top of our garden wall. I had to stand on a garden chair and with heart thumping, carefully approach the bee for a shot. I then realised it was caught in the edge of a spider's web and through the view-finder; I saw the spider appear! It hesitated though and the bee strugged further through the web, me taking shots as it went. Fearing the spider might return, I carefully picked the bee from the web with a twig; hoping to get some better images in a more suitable spot. It flew away though before I got down from the chair!

Eight species of Coelioxys bees have been recorded in the UK. I'm advised that this one may be C. rufescens or C. inermis; both (like all species), rarely recorded in Warwickshire. So all in all, a great few days of "bee spotting" for me! Can I match it as the summer progresses?

(Click on any image for a larger view)

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