Relationship between body size and homing ability in the genus Osmia (Hymenoptera; Megachilidae)

1. The maximum homing ability of female bees, that is, their capacity to return to the nest after being displaced a certain distance, is considered to be an estimate of their maximum foraging distance. 2. The present study provides data on homing ability and body weight for Osmia lignaria and combines them with data for five other congenerics, O. rufa, O. cornuta, O. pedicornis, O. cornifrons, and O. emarginata for analysis. These species are important pollinators of spring-flowering plants, and some have been developed as commercial crop pollinators. 3. It is shown that homing ability is positively and linearly related to body weight (r(2) = 0.81; P = 0.01). 4. These results should be of use in selecting Osmia species as potential crop pollinators and establishing adequate buffer distances around genetically modified crops.