When I discovered this insect in our garden I thought at first it was a bee-mimicking hoverfly as it would rest a while on a leaf, then take off and hover around for a minute or two before returning to its resting place. Having failed to find a hoverfly fitting the description I widened my search and discovered that it is, in fact, a bee - the wool carder bee (Anthidium manicatum). It is related to leaf-cutter bees but this one does not cut up leaves it gathers (cards) fibrous hairs from the leaves of some garden plants to line its nest.
This particular specimen is a male. He spent several days in our garden around a flower that has very white furry leaves and he used that as his base camp. He waited around that plant wishing and hoping a female might come by to gather woollen material for her nest; if one did I am pretty sure he was ready to strike! Whether he was lucky I do not know, one day he was gone never to be seen again.