Bees (Hymenoptera: Apoidea) are the most important pollinators due to their active collection of pollen and frequent visits to flowers. Although honey bees (Apis mellifera) are still the most economically important commercial crop pollinators, other bee species are being developed, including the mason bees (Hymenoptera: Megachilidae: Osmia), which are efficient pollinators of tree-fruit crops. However, we still need to improve the management of these bees and understand how they use resources in their environment. I studied the nesting preferences, soil use and pollen preferences of two common mason bees in Michigan: Osmia lignaria and O. cornifrons. Several nesting shelters and nesting substrates were offered to bees, revealing that the combination of wooden shelters with natural reeds and an attractant resulted in the most nesting. Analysis of soil brought back to the nest showed that most nest partitions are loam or sandy loam, with the two species showing different soil preferences. In the brood provision, even when the nests were in the center of a large blueberry field, O. lignaria did not use this crop as a dominant pollen resource. Results presented here will help to improve management of these bees by offering more suitable nesting materials and shelters, as well as highlighting that O. lignaria is likely not very suitable for blueberry pollination. The soil texture analysis provides new insights into the soil preferences and requirements of mason bees.
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