Center for Biological Diversity

For Immediate Release, February 7, 2022


Jess Tyler, (406) 366-4872,

Variable Cuckoo Bumblebee Moves One Step Closer to Endangered Species Act Protection

WASHINGTON— The U.S. Fish and Wildlife Service announced today that the variable cuckoo bumblebee, a critically imperiled species that has not been observed since 1999, may warrant Endangered Species Act protection. The announcement kicks off a one-year status assessment of the species.

Today’s positive finding comes in response to a petition filed in 2021 by the Center for Biological Diversity. If the variable cuckoo bumblebee gets protected under the Act, it would be the first cuckoo bumblebee listed and the third listed bumblebee after the rusty patched bumblebee and Franklin’s bumblebee.

“These bumblebees need protection urgently, and if the Biden administration acts quickly, we can safeguard this important species before it’s gone forever,” said Jess Tyler, a Center staff scientist who authored the petition. “I’m hopeful that the variable cuckoo bumblebee is still out there, but we need swift federal action to help this species avoid extinction.”

The variable cuckoo bumblebee was once widely found in open grasslands and meadows. While it has lived mainly in the eastern United States, it has also been observed as far southwest as Arizona and as far northeast as New Hampshire. It was last seen in the 1990s in Nebraska, Missouri and Florida. There have been no confirmed observations of this species since 1999.

Cuckoo bumblebees are social parasites that take over the nests of other bumblebees by subduing the resident queen and tricking the host’s worker bees into feeding and caring for the cuckoo bumblebee’s young. In doing so, cuckoo bumblebees help keep host bumblebee populations diverse and healthy, including by reducing disease virulence.

The variable cuckoo bumblebee is entirely dependent on its host species, the American bumblebee, which has declined by an estimated 89%. The Center has also petitioned to list the American bumblebee under the Act and is fighting to get it protected. The variable cuckoo bumblebee and its host are also threatened by multiple concurrent factors that degrade their habitat, including intensive agriculture and pesticides.

The Service will now initiate a scientific status review and public comment period before deciding whether to protect the variable cuckoo bumblebee.


Wild bees are essential to the pollination of wild flowering plants and many flowering crops. North America is home to 46 species of bumblebees, but an increasing number are in trouble. Nearly 1 in 4 bumblebee species is in decline and threatened with extinction in North America.

The variable cuckoo bumblebee is a generalist pollinator and was once found in a wide range of open habitats, including urban areas. Their host species makes its nests in pre-existing cavities, like rodent burrows and rotten logs, or on the surface of the ground in large grass bunches. The variable cuckoo bumblebee is one of a rare group of parasitic cuckoo bumblebees that play important regulatory roles in bumblebee communities and ecosystems.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.

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