Excavator: Ground. This bee occasionally nests in huge compact aggregations, especially in the north of its British range; for example, in North Yorkshire an aggregation of 60-80,000 nests occurred along a 100 m length of river bank (see photograph in O'Toole & Raw, 1991). However, most nests in southern England are generally found in much smaller groups. These occur in both level and vertical exposures of sandy or light soil, including sandstone cliffs, the sides of sandpits and, in one instance, the soil attached to the roots of an upturned tree. In Strathclyde some nesting burrows were found between paving stones (G.M. Spooner, pers. comm.).