PORTLAND, Ore.— The U.S. Fish and Wildlife Service proposed today to protect Suckley’s cuckoo bumblebees under the Endangered Species Act.

This decision comes in response to a petition and legal action by the Center for Biological Diversity.

“It’s so encouraging that the Service has stepped up to protect Suckley’s cuckoo bumblebees,” said Jess Tyler, a staff scientist at the Center and coauthor of the 2020 petition that sought federal protection for the species. “These unique parasitic bumblebees play important roles in keeping bumblebee populations diverse and healthy.”

Suckley’s cuckoo bumblebees have already declined by more than 90%, mirroring the decline of western bumblebees. The decline of western bumblebees has been disastrous for Suckley’s cuckoo bumblebees, who rely on western bumblebees to complete their life cycle.

Climate chaos, intensive pesticide use, and disease have driven declines in Suckley’s cuckoo and western bumblebees. If protected, Suckley’s cuckoo bumblebees will join rusty patched bumblebees and Franklin’s bumblebees as protected species under the Endangered Species Act.

Background

The decline of Suckley’s cuckoo bumblebees is part of a troubling downward trend in which 1 in 4 bumblebee species is in decline.

Suckley’s cuckoo bumblebees are social parasites who play important regulatory roles in the health of bumblebee communities. Female cuckoo bumblebees 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.

Suckley’s cuckoo bumblebees 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, once-common western bumblebees — who have themselves declined by 93% — as well as by habitat degradation, overgrazing, pesticides, and climate change.