Sometimes adding a new plant to your yard can unexpectedly bring in exciting new animals. When our recently-planted potato bush began to flower, we started to hear a novel sound from its vicinity. The bush seemed to be bizzing. Bizz, bizz, bizz.
Upon investigation, the sound turned out to be these striped bees, a species of digger bees. The potato bush has deep purple flowers which produce only powdery pollen, not nectar. The center of the flower is a yellow knob. The bees fly into the center, grasp the knob, press their abdomen against it, and then bizz. The vibration produced causes to knob to release pollen like a salt shaker releases salt. The pollen sticks to the fuzzy body of the bee as the bee flies on to the next flower.
What do the bees do with the pollen? They groom it from their bodies, form it into clumps, and mix it with nectar to feed to their larvae. When bees make a noise to release pollen from a flower it is called buzz pollination.
When carpenter bees visit the plant, they make a deeper buzzing tone, as you would expect with their larger bodies.
Tomato flowers are similar in structure to our potato bush. When people grow tomatoes in greenhouses, they may actually bring in bumblebees to perform the task of buzz pollinating their crops. For more information, visit the GEARs website. (link broken)