In my house wall.
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I find Osmia difficult to identify from photos - how did you decide this one was O. leaiana? O. leaiana usually has a slight metallic blue sheen to the abdomen that I can't see here, but that doesn't always come over in photos.
Nice shot of the bee and its nest.
Entomologist and biological recorder
Thanks for the comment Martin. I'm fortunate to know Steven Falk the entomologist and bee expert. He confirmed this one for me. He said that the box-shaped head was typical and that's what to look for. I also had other shots of the same bee as her nest hole was in my house wall and I watched her for several days.
That's fine Ed, and good to know how Steve arrived at his conclusion. In general I think it would be best if you could put this information in the ID comments when you add an ID that has been given by someone else, just to make it clear how the ID has been arrived at. It's great to have insect photos on iSpot that have been confirmed by a national expert such as Steve, but it's good to be clear about it when that is the case, and provide some acknowledgement to Steve.
Lat/Lng: 52.1, -1.6
OS grid ref: SP3155