Fig. 5. (A) The relationship between wingbeat frequency (wingbeat frequency) and total mass (bee + load, in mg) in pollen (open circles) and nectar (filled circles) foragers hovering in the Regression experiment. There was no significant effect of behavior or total mass on wingbeat frequency (see Table 2). (B) wingbeat frequency versus thorax mass in Regression experiment. For pollen foragers (solid line): wingbeat frequency=269–0.96 (thorax mass), r²⁼0.124, N=37, P=0.035; for nectar foragers (broken line): wingbeat frequency=276–1.12 (thorax mass), r²⁼0.130, N=49, P=0.025. The slopes differed significantly (analysis of covariance, F_{3,7 1}= 3.56, P=0.020).