Two Form Bumble Bee

I spent some time in Steamboat Springs, Colorado last summer. I visited the Yampa River Botanic Park1 three times while I was there. The park is compact and features trees, shrubs and flowering perennials, both native and exotics from around the world. I went there because I thought there was a good chance that I would find some native bees and butterflies.

One of the bumble bees I found in the park was a female Colorado Black-notched Bumble Bee, also know as the Two Form or Two-form Bumble Bee. The scientific name for this bumble bee is Bombus bifarius. (Scientific names are usually consistent across the resources I consult, but common names can be variable.) This bumble bee was collecting pollen or nectar from a Cream Pincushion flower, scientific name Scabiosa ochroleuca, a native to Europe and western Asia.2

Bumble Bees are generalists with respect to flower resources, which means they can find they can and will visit a wide variety of flowers to obtain food for themselves, the queen and developing young bumble bees. Being a resource generalist is a good thing for bees and other pollinators, it is an evolutionary advantage that allows a species to adapt to changing conditions in habitat and climate. The native flower species that they evolved alongside, that they may have visited for food one thousand years ago may no longer be present, in parts of their range.

While there were lots of wildflowers and perennials blooming along the trails at nearby Emerald Mountain,3 with their own cohorts of native bees and butterflies present, the Yampa Valley Botanic Park provides an oasis with food and shelter located in a more residential area. Each spring and summer it supports native bee populations that might not be present in that particular location if the Park was not there. During my third visit at the Park I signed up to become a member. I hope to be back for another visit or two this summer.

A Bombus bifarius on a Scabiosa ochroleuca flower. The bumble bee is black with light yellow and orange markings. She appears to be collecting nectar from the flower which is a composite type of flower with larger white rays around the outer edge and many smaller florets in the center that comprises most of the flower. The bee has pollen that she has collected on her hind legs.
A Bombus bifarius on a Scabiosa ochroleuca flower. The bumble bee is black with light yellow and orange markings. She appears to be collecting nectar from the flower which is a composite type of flower with larger white rays around the outer edge and many smaller florets in the center that comprises most of the flower. The bee has pollen that she has collected on her hind legs.
  1. Yampa River Botanic Park. Website accessed on January 4, 2025. ↩︎
  2. Bombus bifarus, Two Form Bumble Bee. Bumble Bees of the Western United States. USDA Forest Service and the Pollinator Partnership. Xerces website page accessed on January 4, 2025, (PDF pp. 78-81). ↩︎
  3. The Emerald Mountain Special Recreation Area (SMRA). Bureau of Land Management, U.S. Department of the Interior. Website accessed on January 4, 2025. ↩︎

By S. Felton

S. Felton is a writer, photographer and amateur naturalist.

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