Three female Carpenter bees were sighted on this bush. A male turned up and two of the females left. The male flew around the remaining female who then stopped collecting pollen and took up the posture seen in the images. Mating took place in the sequence shown in the images with the male initially flying close to the left side of the female as seen in the second image. Mating occurred just after the fourth image was taken. The male then backed away as seen in the last image and left, with the female going back to pollen collection. Thanks to Marcus Leach for originally locating the Carpenter bees on this plant.
A lovely sequence. If more than one male is present, the female may lead them in a vertical zig-zag dance which may be part of a mate selection behaviour.