The second generation of the mining bee Andrena argentata found in the calcium-poor dunes near Schoorl appears to be monolectic. The females gather pollen from common heather (Calluna vulgaris). Both the scopa and the nest cells of this bee contain pollen only from this plant. The nest is of the type 'singly branched,' subtype 'branched at different levels.' I found the pupa of a fly in the body of a dead bee in one nest cell; I will have to watch this fly emerge.