Photo Date/Time: April 03, 2010
Photograph By: Eddie Dunbar
Yellow-faced Bumble Bee
Description: Guide to the Bombus of San Francisco, By Quinn S. McFrederick, B. vosnesenskii, B. caliginosus and B. californicus all have yellow hairs at the front and back of their bodies and a large black patch in the center. B. vosnesenskii is the most common and has short hairs that looked cropped and yellow hairs on the face. B. californicus is the only one of the three with black hairs on the face. B. caliginosus is shaggier than B. vosnesenskii and has yellowhairs on the underside of the abdomen where B. vosnesenskii has only black hairs on the underside of the abdomen. Wikipedia: Bombus vosnesenskii, the Yellow-faced Bumblebee, is distributed through western North America. This species grows to 1-2 centimetres (0.39-0.79 in) long, with queen being larger than the workers. B. vosnesenskii is characterized by the yellow coloration of the head pile, the mostly black thorax and abdomen, a single yellow thoracic stripe on the lower abdomen, and blackish wings.
Colors: Top and front of area forward of eyes with yellow setae. Thorax with yellow setae at anterium and black setae at posterium. Abdomen all black except for a segment before the apex which is ringed in yellow.
Body Length: 15-22 (Q); 10-17 (W)
Biology: Wikipedia: The overwintering queen first appears during spring and establishes underground colonies. After laying her first brood she, and the workers, will incubate the cluster until the adults emerge. The queen and workers use thermoregulation to incubate the cluster. The fuel for the bumblebee's thermoregulation during incubation is derived from honey (when the bumblebee is not foraging), nectar, and pollen. Late in the season males and young queens leave the nest and mate. While old males, queens, and workers die. The new queens overwinter and the cycle continues.
Range: Bombus vosnesenskii is found along the west coast from southern British Columbia to northern Baja California. It is very common in much of its range.