The behaviour of bees visiting runner beans (Phaseolus multiflorus).
The following is virtually the author's summary of this account of investigations on the pollination of runner beans (Phaseolus multiflorus[Phaseolus coccineus]) in southern England [cf.RAE A 57 546]. Foragers of Bombus agrorum (F.) entered the mouths of runner bean flowers and collected either nectar only or nectar and pollen; some of these bumble bees kept constantly to one or other occupation. Most foragers of B. lucorum (L.) and B. terrestris (L.) obtained nectar through holes bitten in the bases of the corolla tubes. Most honey bees collected nectar either by entering the flowers or by robbing nectar through holes bitten by B. lucorum and B. terrestris; very few collected pollen. The number of honey bees robbing the flowers depended on the numbers of B. lucorum and B. terrestris present. Nectar-gathering honey bees readily changed from robbing to collecting nectar through the mouths of the flowers and contrariwise. The numbers of bumble bees and honey bees gathering pollen were greatest between 8 and 10 a.m., and the numbers robbing were greatest during the late afternoon. Bumble bees worked faster and visited more flowers per plant than honey bees. Their foraging areas on a single trip were probably no greater than those of honey bees. However, they were larger during several trips.