Het voorkomen van de graafwesp Crossocerus walkeri in Nederland, met bijzondere aandacht voor het emplacement van Westervoort (Hymenoptera: Crabronidae)

The occurrence of the digger wasp Crossocerus walkeri in the Netherlands, with special attention for locality ‘Emplacement van Westervoort’ (Hymenoptera: Crabronidae) The Dutch records of the rare digger wasp Crossocerus walkeri are illustrated and discussed. Special attention is given to the locality ‘Emplacement van Westervoort’, an abandoned railwayyard. This is the only recent site where more than one specimen was collected since 1980.