De rotsbehangersbij Megachile pilidens, nieuw voor de Nederlandse fauna (Hymenoptera: Apoidea: Megachilidae)

Megachile pilidens new for the Netherlands (Hymenoptera: Apoidea: Megachilidae) Megachile pilidens Alfken 1924 is reported for the first time from the Netherlands. We also mention some new records in adjacent parts in Germany and Belgium. In Europe M. pilidens has a south-eastern distribution but recently expands to the north. Its occurrence seems to be associated with rocky or stony habitats. The Dutch records in 2005 and 2006 are four females and one male from different sites, all collected in the vicinity of (limestone) quarries in the southernmost part of the province of Limburg. The recent expansion is discussed and some data are presented on host plants and differences with the sibling species M. leachella.