I think this is a leaf-cutter bee species from the genus Megachile, I'd appreciate it if someone could confirm that. If you could also tell me which species it is that would be great. She has been trimming neat curves from the leaves of the Epilobium which liberally weed my garden, though I am more than happy to leave them for her!
This bee is a Megachilidae(a family of bees), most commonly known as, a 'leaf-cutter bee'. They use the leaves, petals etc. to create 'nests', as they are called, for themselves and are more solitary than other bees. They are native to North America but can be found in other countries too. They are extremely inefficient at collecting pollen unlike other bee families.