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Bumblebees pollinating Boulder raspberry- Rubus deliciosus
In Crestone, Colorado at 8,500′

Just as we gather berries in a basket, bees gather pollen and nectar in their own specialized pollen baskets. On bumblebees these are called curbiculae. The curbiculae, or pollen basket is a smooth concave area on the outer side of the hind leg. In some of the bumblebee photos below you can see the pollen loading up in the curbiculae. Long hairs around the curbiculae hold the pollen in place. They can only carry so much pollen and still be able to fly, so once the baskets are full, they take off back to the nest and empty the pollen/nectar load.

Native bumble bee

A very clear view of the corbiculae on the hind leg of this bumblebee. This one is getting pretty full, but I have seen them twice this full! ┬ęCarol English

While I observed the bumblebees on the Boulder raspberry flowers, I noticed the bees avoided most of the fully open flowers, and most often went for the flowers that were partially open. I am certain the bees can determine which flowers have already been visited, and they avoid those and search for flowers that are loaded with more pollen.They were very active, making it difficult to photograph them. They would slam into a flower and make a low buzzing sound.

Native bumble bee

These native bumble bees seemed to prefer flowers not yet fully opened. ┬ęCarol English

How could you ever be bored on this planet? You do not even need to travel far. Just go stare at a Boulder raspberry shrub in bloom, and your world becomes so rich and exciting.

Carol English
Native Plant Master