Osmia leaiana - a small Mason Bee

16th July 2012
It's another disappointly cold and wet July day and the local bees (apart from some typically tough bumblebees) have all decided to remain tucked away in their hiding places. Feeling the need to add another post to my Blog, I decided to see what I was photographing this time last year.

Last year was the first that I had become really interested in learning more about our local solitary bees, so everything I saw was a "first". I have seen Osmia leaiana on a few occasions this year (mainly at my "Bee Hotel"), but this week back in 2011 was the first time I had seen and photographed it.

Osmia leaiana is related to the larger and more common Osmia bicornis (=O. rufa); the Red Mason Bee. Both often use holes/crevices in old wood and walls to construct their nests. This is just what this female had done, choosing a little hole in the brickwork just by our front door. Unlike the Red Mason Bee though that uses mud to create brood cell partitions and to seal the nest entrance, Osmia leaiana uses chewed leaves.

The image top left is one of my favourites. Having established her nest, the female bee would look out in the morning; guaging whether it was warm enough to venture out. On this occasion as I took the shot, she reacted to the flash with this rather startled expression (if bees can have expressions!).

The three images directly above show (left) - the bee resting on the wall in the sunshine, (middle) - returning to the nest with a pollen load and (right) - initially investigating the hole as a potential nest site. You will see too that like all Osmia bees (and other genera in the subfamily Megachilinae), Osmia leaiana females carry pollen on rows of hairs beneath the abdomen (the scopa). With this species, the hairs are orange. The other regularly seen small species Osmia caerulescens (the Blue Mason Bee), has black scopal hairs.

I really hope that as the weather improves, I see more of these lovely little bees in the garden.

(Click on any image for a larger version)

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