Nomadic

By the time a cool and murky day gave way to a beautiful, sunny evening, I had done my gardening and bug hunting, and was busy with other concerns, so I probably missed out on most of today's invert activity. However there are two advantages to looking for invertebrates in dreary conditions: when you can find them, they tend to sit still while you photograph them, and flatter light generally produces better images.

This nomad bee was so passive while I worked around him with the camera that I had my pick of angles, and I think I tried most of them to capture him in as much detail as possible. Had I known that he wasn't going to move from this spot for almost an hour, I'd probably have fetched a tripod and used a lower shutter speed to reduce the ISO, or maybe even taken multiple frames for later focus stacking, but for a single image captured hand-held in poor light, I'm pretty happy with this. 

The tri-coloured nomads are notoriously difficult to identify to species, and when asked even the BWARS people will often swerve the question, but I'm prepared to stake a claim here and say that this is a male Nomada lathburiana. This is one of the larger nomad species, at 7-9mm in length. Both sexes have the same red, black and yellow abdominal banding, but in other ways they're quite distinct. Females have an obvious red pile over their black thorax; their eyes and lower face are also red, as are their legs and tegulae, while their antennae are entirely orangey-red. Overall, they look slightly demonic. Males are much paler, with a lighter pile (though still auburn, as you can see here), a yellow face and tegulae, paler eyes and legs, and tricoloured orange, black and yellow antennae. The clinching feature that separates Nomada lathburiana males from similar nomads is that the hind faces of their antennae have tiny, sharp projections - not obvious here, though you can see the ghost of them in a line of paler marks along the length of the nearer antenna, but clearly visible in some of my other shots.

Nomada lathburiana is a cleptoparasite of the ashy mining bee, Andrena cineraria, the female nomad laying a single egg in the wall of an ashy miner's nest cell while the host mother is still in the process of provisioning it. Provisioning complete, the Andrena cineraria female seals this nest cell and moves on, unaware of the parasitic egg, which hatches into a larva that consumes both the host egg and its food supply before pupating. Andrena cineraria numbers in this area seem to have been falling over recent years - it used to be one of the earliest and most common miners in my garden and the surrounding area, but last year I saw many fewer than usual, and so far this year I've only seen one individual - but the presence of its cleptoparasite makes me think that there must still be a viable Andrena cineraria population here.