Some estimates suggest that bumble bees are believed to be responsible for the pollination of approximately 25% of crops in northern California. Even after we add honeybees to the farm next spring, it will still be critical to encourage and support our native bee populations to help ensure that our gardens thrive year-round .
In early spring we were delighted to see hoards of native yellow-faced bumble bees (Bombus vosnesenskii) lurking in the lavender, and recently we sighted some native sweat bees on the Verbena and heirloom sunflowers in the gardens.
However, over the weekend we found this large and beautiful bumble bee lazily meandering around the Dotted Mint (Monarda lambada) in the herb garden, and thankfully she didn’t seem to mind the camera’s lens in the least.
After some sleuthing, this female worker appears to be the edwardsii subspecies of Bombus melanopygus, also known as the Black-tip Bumble Bee [2,3]. She was a large bee, and not particularly fast moving.
Identifying her was a little challenging, but one distinguishing feature for this species is the black band running from side to side on the thorax, which is surrounded by yellow hairs.
The face of Bombus melanopygus edwardsii is light in coloration, similar to the yellow-faced bumble bee.
The abdomen is divided into 6 (female) or 7 (male) segments, called ‘terga’. Tergites 2 and 3 provide important clues for identifying this subspecies, which are rufous red in the species B. melanopygus, but black in the subspecies B. melanopygus edwardsii.
In addition to these black hairs, B. melanopygus edwardsii has thick yellow hairs on tergites 4 and 5, with a black tail tip.
Although the yellow-faced bumble bees seem to be the most prevalent here, we do occasionally see other species, but this is the first time we’ve been close enough with the camera to identify one of the other Bombus species lurking among our flowers.
Bombus melanopygus edwardsii is native to western North America. This subspecies reportedly nests both above ground, occasionally using old bird nests, and underground in small hollows and rodent burrows, and with an abundance of both on the property, we hope they find some suitable nesting habitat here.
Honeybees usually come to mind as the most prevalent pollinators in most gardens, and as such many native pollinators are frequently overlooked. We’re now making an effort to pay closer attention to both the prevalence and diversity of our native pollinators here, and hope, through continued plantings of various native plant species over time, to encourage many more of our native bee species to visit our gardens. I wonder who we’ll see next?
 Guide to the Bombus of San Francisco (PDF)
 Discover Life Online Key to Bumble Bee Species