I am in the process of tweeking a macro photography presentation for tomorrows workshop at the Ellis Bird Farm, when I came across this pic. Photographed in the front garden, this Bombus nevadensis queen is visiting the flowers of blue indigo (Baptisia australis), a favorite of the many smaller leaf-cutter bees we have had in the garden this year. The E.H. Strickland Entomological Collection page has a great description on the life history of this bee, authored by L. Vandervalk (2011) and based on D.V. Alford’s book, Bumblebees (1975):
Once a suitable nest has been found, the queen constructs an apple sized hollow structure within it. The queen deposits her eggs in parallel rows within a mound of pollen on the floor of the structure; she also constructs a honeypot for storing nectar. Newly hatched larvae begin consuming the pollen mound, requiring the queen to continue provisioning it. The queen periodically incubates her brood by sitting upon it and respiring to generate body heat. The larvae spin cocoons in the final instars, as do the pupa; the cocoons may be re-used later for storage of pollen or nectar. Upon pupation, the emerged adults take nectar from the honey pot. Once the nest consists of the new young workers and the queen it can be considered a social unit and is referred to as a colony.
Yes, this queen incubates the young! Read the complete description at the species page.
Thanks to Gary Anweiler for the ID!