Hello,
As I am interested in several Hymenoptera families (I begin with aculeate "wasps", Spheciformes, Vespidae, Sapygidae, Pompilidae) & bees (especially Megachilidae, but others groups too, in my region), I search many papers on internet : one great specialist of bees is Andreas Müller (taxonomy, ecology).
This specialist of trib Osmiini (solitary Bees : Megachilidae), found some nests of the rare Osmia pilicornis and Chrysura hirsuta is mentioned as cleptoparasit of the bee.
More information in this paper : here