Center for Biological Diversity

For Immediate Release, October 25, 2022


Jess Tyler, (406) 366-4872,
Kylah Staley, (626) 736-0587,

Rare Cuckoo Bumblebees Move One Step Closer to U.S. Endangered Species Protection

TUCSON, Ariz.— In response to a lawsuit by the Center for Biological Diversity, the U.S. Fish and Wildlife Service agreed today to a deadline of December 2024 to determine whether Suckley’s cuckoo bumblebees warrant protection under the Endangered Species Act.

The species has already declined by more than 90%. Over the past two decades, a few scattered individuals have been spotted in California, Alaska, Idaho, Oregon, Colorado, Wyoming and Montana.

”This is great news for these critically imperiled bees,” said Jess Tyler, a staff scientist at the Center and author of the 2020 petition that sought federal protection for the species. “Protecting pollinators like the Suckley’s cuckoo bumblebee is vital in the face of our current insect apocalypse.”

Suckley’s cuckoo bumblebees have a fascinating story — although their specific methods remain unknown, females must fight or sneak into a colony of western bumblebees, then kill or subdue the host colony’s queen. The cuckoo bee then lays her own eggs and gains control of the host colony’s worker bees, who continue collecting pollen and nectar to feed the cuckoo bee’s offspring.

The parasitic cuckoo bumblebees play important regulatory roles in maintaining the health of bumblebee communities and the diversity of ecosystems.

Suckley’s cuckoos are generalist pollinators and feed on flowers in the aster family, as well as many other wildflower meadow species. They were once common in prairies, meadows and grasslands across the western United States but have now been lost across more than 50% of their historic range.

The bees are threatened by declines in their host species, the once-common western bumblebee — which itself has declined by 93% — as well as by habitat degradation, overgrazing, pesticides and climate change.

The last sighting of a Suckley’s cuckoo bumblebee was in Oregon in 2017.

As a result of a separate legal agreement, the Service plans to decide in 2024 whether the western bumblebee deserves protection.

The Center for Biological Diversity filed a lawsuit against the Service in April 2022 for failing to meet a 2021 deadline to issue a final listing decision for Suckley’s cuckoo.

“For far too long the Service has ignored mounting evidence of this bumblebee’s troubling decline toward extinction,” said Kylah Staley, a legal fellow at the Center. “This agreement marks a long overdue step in preventing this important species from disappearing forever.”

Today’s agreement between the Service and the Center for Biological Diversity was approved by U.S. Magistrate Judge Jacqueline Rateau in the U.S. District Court of Arizona.

The decline of the Suckley’s cuckoo is part of a troubling downward trend in many of the 46 species of bumblebees and approximately 3,600 species of native bees in the United States.

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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