Nesting biology of Osmia pilicornis uncovered
The nesting biology of the rare European osmiine bee species Osmia pilicornis was still unknown. The recent discovery of several nests in Germany and Austria by Prosi et al. (2016) revealed that this species has a unique nesting behaviour among the osmiine bees: the females gnaw their nests with the aid of specialized mandibles in dead branches, which lie on the ground and are partly hidden under vegetation. Recently, Lemoine (2016) also discovered a nest in northern France, which was built in a branch of Populus; in contrast to his statement in the article that a preexisting beetle burrow served as nesting site, the female bee actually tunnelled out the nest by herself (personal communication by G. Lemoine) supporting the findings of Prosi et al. (2016). For details on nesting site and nest architecture see the species account on the Palaearctic osmiine bee website.