A few solitary bees also visit foxgloves. In my garden the forked tailed flower bee Anthophora furcata regularly visits them, and more rarely the carder bee Anthidium manicatum.
As relatively few species feed on this species, it is a good starting plant to familiarise yourself with bumblebees.
Today, I watched four bee species visiting this particular foxglove stem.
B. pascuorum is the most common all-brown bumblebee in gardens.
Bombus hypnorum is a very distinctive bumblebee, three coloured: brown/black/white.
The stout black abdomen with lateral yellow patches of the Wood Carden Bee Anthidium manicatum which visited on 1/07/2011.Foxglove flowers open from the bottom of the stem towards the top. The plant reproductive parts are located on the roof of the flower, four stamens and a pistil in the middle, so that the body of a bumblebee entering the flower rubs against them. To reduce self-pollination, the flower anthers open first, delivering a pollen load onto bumblebees feeding. Five days later, when the pollen is likely to be exhausted the pistil becomes receptive, increasing the chances that it will be pollinated by the pollen of a different plant. I cut three flowers of a white foxglove in the garden and removed the roof of the flower to expose the reproductive organs. The one on the left, from the top of the flower spike just opened. The lobed yellowish sacs are the closed anthers, and the spike in the middle is the pistil, also closed and attached to the flower roof. The middle flower has open anthers and the pistil, although closed, has started to detach. On the left is the oldest flower from the bottom of the flower spike. Its anthers are almost devoid of pollen and the pistil is now pointing down, so that is easily rubbed by the bumblebee's back and then ready to be fertilised.
A bumblebee view of a foxglove. Note the open pistils on the lower, older flowers.
Arthur A. D. Broadbent and Andrew F. G. Bourke (2012). The bumblebee Bombus hortorum is the main pollinating visitor to Digitalis purpurea (Common Foxglove) in a UK population. Journal of Pollination Ecology, 8 (7), 48-51.