I’ve been keeping watch on the Evening Primrose to find out what insect is responsible for pollination and have finally found a likely candidate. There have been no late night moth visitors, but I’ve seen a lot of early morning Carpenter Bee activity.
Pollen grains on the body and legs of the bee suggest effective transport of pollen between flowers. This is what you would expect from a bee. The unusual aspect is the method in which the Carpenter Bee collects that pollen.
The bee lands on the flower, but it doesn’t stay there. Immediately after setting down, the bee crawls on over the flower and begins moving down the stem. The trip across the flower is the maneuver that deposits pollen.
At a point on the stem just below the flower, the bee gets itself carefully positioned.
Then it hugs tightly to the stem and vibrates, an action known as buzz pollination. The pulsations from the vibrating bee cause the pollen grains to fall from the flower’s anthers.
In some types of flowers the pollen falls onto the bee. I’m not sure the shape of the primrose bloom allows much of the pollen to fall free of the flower, so buzz pollination wouldn’t appear to be the best strategy for this species. The fact that the method is working for both bee and flower suggests that I don’t know everything there is to know about pollination methods. Animals do what they do because it works. I shouldn’t be second guessing their actions.