Thorp and the Xerces Society petitioned USFWS on June 23, 2010, for endangered status for the bumble bee. USFWS announced, "Based on our review, we find that the petition presents substantial scientific or commercial information indicating that listing this species may be warranted. Therefore, with publication of this notice we are initiating a review of the status of the species to determine if ... Franklin's bumble bee may warrant protection under the U.S. Endangered Species Act."

The International Union for Conservation of Nature (IUCN), the world's oldest and largest global environmental network, named Franklin's bumble bee "Species of the Day" on Oct. 21, 2010. IUCN placed it on the "Red List of Threatened Species" and classified it as "critically endangered" and in "imminent danger of extinction."

Franklin's bumble bee, mostly black, has distinctive yellow markings on the front of its thorax and top of its head, Thorp said. It has a solid black abdomen with just a touch of white at the tip, and an inverted U-shaped design between its wing bases.

"This bumble bee is partly at risk because of its very small range of distribution," he said. "Adverse effects within this narrow range can have a much greater effect on it than on more widespread bumble bees."

If it's given protective status, this could "stimulate research into the probable causes of its decline," said Thorp, an active member of the Xerces Society. "This may not only lead to its recovery, but also help us better understand environmental threats to pollinators and how to prevent them in future. This petition also serves as a wake-up call to the importance of pollinators and the need to provide protections from the various threats to the health of their populations."

Thorp hypothesizes that the decline of the subgenus Bombus (including B. franklini and its closely related B. occidentalis, and two eastern species B. affinis and B. terricola) is linked to an exotic disease (or diseases) associated with the trafficking of commercially produced bumble bees for pollination of greenhouse tomatoes.

Other threats may include pesticides, climate change and competition with nonnative bees, according to Xerces Society executive director Scott Hoffman Black. Said Sarina Jepson, endangered species program director at the Xerces Society: "Bumble bees play a critical role in ecosystems as pollinators of wildflowers, as well as many crops. We hope that the service will ultimately provide Endangered Species Act protection to this important pollinator."

Named in 1921 for Henry J. Franklin, who monographed the bumble bees of North and South America in 1912-13, Franklin's bumble bee frequents California poppies, lupines, vetch, wild roses, blackberries, clover, sweet peas, horsemint and mountain penny royal during its flight season, from mid-May through September. It collects pollen primarily from lupines and poppies and gathers nectar mainly from mints.