Tunnel lengths average almost 4.5 inches and chimney lengths vary, sometimes reaching more than three inches. Within each tunnel, five to eight cells are excavated and then lined with a clear fluid released from the Dufour's gland on the abdomen. This lining adds strength and water-proofing to the cell. Last instar larvae may also obtain nutrients by consuming this layer. Eggs are laid atop the pollen mass.
Cells are capped with clay and eggs hatch about five days later.
After all cells in a nest are completed, the tunnel is stopped with a plug of packed clay. Immediately inside the tunnel plug and before the first cell is an empty chamber. This may be to discourage predation or allow safe emergence of new bees. Females collect pollen from many sources, but do not mix pollen within any foraging trip. Individual females live 4-6 weeks while male lifespan is less than half as long.