Morrison bumble bee, Bombus morrisoni

Please reference the Embedded Range Maps page to better interpret
# of observations per ecoregion.

The Morrison bumble bee, Bombus morrisoni is very rare in Washington state. There is evidence that the range of B morrisoni’s has been strongly contracting over the last decade or so. There is at least one population of morrisoni remaining in Washington and we hope we can locate others. Similar to what is being seen in Oregon, bumble bees in central Washington seem to be utilizing the urban areas. This may be climate change related, in that it has been so hot and dry many fewer nectar and pollen resources are available in the native landscapes so the urban centers with planted mints and other pollinator plants offer a greater diversity of flowering resources, throughout the full season.

If you encounter a suspected morrisoni in the field, please get good pictures. A positive ID can be made just from photographs for this species, so it would be better to use a non-lethal approach to documenting any individuals you encounter.

Field ID tips

This is a good sized bumble bee, similar to the Nevada bumble bee.

The Morrison bumble bee has a yellow scutum, alar and scutellum

T1 & T2 are yellow. T3 is mainly yellow but may show some black on the sides.

It has a short cheek.

Similar Species

The Nevada bumble bee is the most similar species. It will show a black dot between the wings and T3 will be all yellow. Relative to the Morrison bumble, nevadensis has a long cheek and therefor a very different face shape.

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