The Western Bumblebee is a species that was once common and widespread throughout the western U.S. and Canada. For a variety of reasons, both known and unknown, populations of this bee are in serious decline. It has mostly vanished west of the Cascades. Thankfully, West Valley is a place (perhaps a refuge?) where the bees may still be found.
We have at least a dozen bumblebee species in West Valley. The Western Bumblebee is relatively easy to identify because it is the only bumblebee in our area with a distinctly white rump. The bald-faced hornet also has a white tail, but appears hairless with a narrow waist and thin wings—distinctly wasp-like compared to the teddy-bear-like short-winged bumblebee. In addition to its fuzzy white tush, the Western Bumblebee has a yellow band across its shoulders. The rest of the bee, including its head, is black. The Two-Form Bumblebee is often black and white, but it does not have the distinctive white tail, and the black forms a narrow triangle on its thorax.
Western bumblebees have short faces and short tongues. This means that they are adapted to open faced flowers such as roses, spirea, and daisies rather than long tubed flowers such as penstemon or columbine. However, they may be known to “nectar rob” long-tubed flowers by chewing through the bottom of the flower to obtain nectar without pollinating the flower.
There are a variety of reasons for the decline of the Western Bumblebee as well as many of our native bees and honeybees. Western Bumblebees were once used commercially to pollinate greenhouse tomatoes. As such, many of them were shipped around the U.S. and Europe where they picked up diseases and parasites. Some infected insects escaped and their pathogens spread.
In addition to diseases and parasites, all bumblebees face hazards from pesticide use, especially neonicotinoid formulations. These pesticides are commonly used on canola crops (95% of canola nationwide) as well as corn, tomatoes, fruit, and seed coatings. Many of these pesticides are widely available. If the product label says “systemic,” the pesticide is usually a neonicotinoid.
There are a variety of ways to help the Western Bumblebee and its other fuzzy cousins, and some are quite fun. Raising native wildflowers that bloom throughout the season is a big help to all pollinators. Leaving things “a little messy” with some tall grass, leaf litter, bare ground and untended spaces, provides sheltering and nesting areas for queen bees. Breaking out your camera and documenting Western Bumblebee sightings as well as other bumblebees can be almost addicting. The Bumblebeewatch.org website is a citizen science site where you can upload photos and locations of bumblebees you find. The site helps you identify species and often, a trained entomologist will verify your finding. Catching a photo of that white tail is key for the Western Bumblebee.