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On a trip to western New York in October, I was taken by how many bumble bees there were.

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Some were resting on leaves, etc.

thistle-bumble-bee-123

Others were collecting pollen and nectar. Because there were so many, in fact, I soon wished I knew how to identify bumble bees better.

It not uncommon to have difficulty identifying bumble bees. Some species vary quite a bit in color and don't have a lot of distinct morphological differences. Much of the bumble bee literature is quite old and the keys are out of date.

Fortunately The USDA Forest Service and The Pollinator Partnership recently have created two identification guides for bumble bees:  Bumble Bees of the Eastern United States by Sheila Colla, Leif Richardson and Paul Williams and Bumble Bees of the Western United States by Jonathan Koch, James Strange and Paul Williams

The two guides can be downloaded as free .pdfs at The Xerces Society (scroll to bottom of page).

(There are free downloadable bumble bee posters at the USDA Forest Service, too -scroll down.)

Looking through the Bumble Bees of the Eastern United States guide, I believe the bumble bee above on the thistle flower is Bombus impatiens, the common eastern bumble bee.

cosmos-bumble-bee-234

 

I can't wait to give the western one a try on the species here in the Southwest.

Have you seen these guides? What kind of bumble bees do you see regularly?

Also, does anyone know of a rather small bumble bee that may have been introduced to western New York?

4

Did you guess what the bumble bees were doing in the post earlier this week?

 

weigela-bumble-bee-2

It seemed like the bees were only visiting the light-colored flowers and were ignoring the dark pink ones.

A little research confirmed this for another species, Weigela middendorffiana. According to Ida and Kudo, the flowers change color from yellow to red inside as they age. This species also is pollinated by bumble bees and the bees ignore the older, red flowers. The color-changed flowers did not provide a nectar reward. The authors suggest the color change may increase pollination success by reducing successive visits to the same flower.

Lupines and lantana also change color after pollination. Do you know of any other plants that do this?

Reference:

Ida T.Y, and G, Kudo. (2003). Floral color change in Weigela middendorffiana (Caprifoliaceae): reduction of geitonogamous pollination by bumble bees. Am J Bot. 90(12):1751-7. (full text)