His data, however, showed that the plants in the cages with bees produced 21 percent more seed weight, with 6 percent more pod weight than plants from which bees were excluded. Beans are visited only sparingly by honey bees, and beekeepers do not consider this crop of significance as a source of nectar or pollen. What the visitation or its effect on beans might be under a high concentration of bees is unknown, but the information would be of interest and possibly of considerable value to bean growers. Those who have studied the problem agree that bumble bees and honey bees are the most frequent visitors to bean flowers in the United States. The data indicate that, if pollinating insects are of benefit, the bumble bee is the best pollinator.
Honey bees are apparently next in importance.
The latter can be increased in numbers where desired. They visit the blossom for both pollen and nectar. The exact effect on the flower or value to the different cultivars of P. vulgaris has not been well established. There are no recommendations on the use of bees as pollinators of beans. In fact bean breeders, knowing the plants will set fruit in greenhouses where bees are excluded, feel that pollinating insects are entirely unnecessary.