A Fresh Bumblebee

An unexpected creature sat warming itself in the sun on the patio this morning: a yellow-faced bumble bee (Bombus vosnesenskii)

 

Its long yellow "hairs" and textured black body appeared fresh and new, as if it had just emerged into adulthood. No pollen clung to its body. Every wing and limb shone iridescent black in the sunlight. Where did it come from? 

Bumble bees typically nest in a cavity in the ground. Waxy cells, each packed with food resources, house the eggs and then developing larva. Once, 14 years ago western bumble bees nested in a birdhouse.

Where did this yellow-faced bumble bee emerge from? This area of the patio is edged with a concrete brick wall along one side and the house on the other. The cold bee was not able to fly; it would've had to walk a distance of 10 or more feet to find this dappled place in the sun.

The large bumble bee sat basking for a good 10 minutes before its body was warmed up enough to fly. Then off it went.

Identifiable by its fuzzy yellow head and a black abdomen with a narrow yellow band on the fourth section (nearly the tip), the yellow-faced bumble bee is a valuable pollinator. Like all bumble bees, however, they struggle to find suitable habitat. The mother of this bumble bee must have appreciated the native plants and undisturbed areas of soil that could provide for her offspring.

On this cool February morning, it seems early for bumble bees to be leaving the safety of their nests. Yet, the morning also brings the spring's first western swallowtail, fiery skipper, and California sister butterflies down into the yard. I wish the bumble bee well and hope we will see it among the sage and coffeeberry. 

Western Bumble Bee Nest

When I went to clean out one of the bird nest boxes, I was surprised to find that a western bumble bee (Bombus occidentalis) had made its nest inside. Typically this kind of bumble bee makes its nest in the ground. But here was the clump of waxy cup-shaped cells described in the books nestled in the dog hair and sticks that the Bewick's wrens had been using to build their nest. (This could explain why the wrens decided to move out and rebuild their nest in the pot next to the back door.)

Alarmingly, all of the bumble bees, adults and juveniles, still developing in their wax cells, were dead. What killed them? Was is the cold weather snap we had in October/November? There was a garden spider in among the corpses. Had this small spider preyed on the bumble bee nest? I can't imagine that it could have gotten to the juveniles in their waxy cells. Was there some kind of mite or fungus that caused the death of all ages? I don't know.

During the winter the queen bumble bee hibernates in a protected location all alone. She will emerge in the spring to start a new colony and then usually die. I hope that there was at least one survivor from this western bumble bee nest. (More on bumble bees: xerces.org) Our native bees are vital pollinators and typically are not susceptible to the same diseases and environmental conditions that threaten European honey bees. Most are not aggressive and are not a threat to people.

We have noticed carpenter bees nesting in the yard before but this is the first time for bumble bees. I've wanted to create a native bee nesting site for some time. It seems now is the time to finally take on that project.