In the spring she builds her nest under the bark of rotten logs. If you thought that dead trees or large dead branches had no use you were wrong. To this very nice pollinator they are prized real estate, just the right place to raise her family safely and well protected. She searches for the right dead tree diligently and, if your garden is one of those perfectly manicure ones, you will not have the pleasure of her and her family's company.
She builds a small chamber in the space between the loose bark and the solid wood using her own saliva and secretions. She packs it with a storage of pollen and nectar very carefully kneaded and shaped as tiny loaves. She encrusts the inner walls of the chamber with these loaves arranged like tiles. When she has enough to feed one baby from birth to maturity she lays a small egg and shuts the chamber. She surrounds it with loose debris which abounds in such places and starts the construction of other chambers. You may find a couple of rows of four or five of these cells. The mother bee dies at the end of the summer and the new generation spends the rest of the year comfortable and safe until the next spring.