Responding to petitions filed by the Xerces Society, last week the U.S. Fish and Wildlife Service (FWS) announced that the Morrison bumble bee (Bombus morrisoni) and the large marble butterfly (Euchloe ausonides) warrant further consideration for protection under the Endangered Species Act, by issuing a positive 90-day finding for these two species.
Next, Fish and Wildlife will carry out a full review (called a Species Status Assessment) of the two species. Once these are completed, FWS will decide whether or not listing these species as threatened or endangered under the Endangered Species Act is warranted. If listing is warranted, legal protections will go into effect and resources will be directed to recovery.
Morrison bumble bees have disappeared in many places
The Morrison bumble bee historically occurred across much of the western U.S., and can be found in grasslands, sagebrush steppe, and woodland edges. It has co-evolved with local plants for thousands of years and is a super-pollinator, contributing to the stability of our wildlands and agricultural systems. However, the species has disappeared from much of its range and may have declined by as much as 75%. It faces multiple ongoing threats, including habitat loss and degradation, overgrazing, climate change, pesticides, diseases, and competition with honey bees. The Xerces Society petitioned FWS to protect this bee in 2023.
Volunteers with the Bumble Bee Atlas program are playing an important role in this story, as their data will be used in the species status assessment for the Morrison bumble bee. The information volunteers gather on bumble bee distribution, threats and population trends is critical to helping species recover, and one of the best ways you can get involved in saving the bees.
Threats loom for the large marble butterflies
The large marble butterfly is a widespread and historically common species across 16 western and midwestern states. Caterpillars feed on various plants in the mustard family, and preferred habitats for the butterfly include grasslands and open meadows along with stream-sides, desert washes, beaches, canyons, sagebrush steppe, montane slopes, open tundra, and weedy flats.
Despite its widespread distribution, recent studies using long-term monitoring data have ranked the large marble as one of the western butterfly species most at risk of extinction in the next 50 years. Xerces submitted a petition for ESA protection in 2023. Populations are threatened by widespread habitat loss and degradation, pesticide exposure, climate change, introduced predators and parasitoids, and inadequate regulation across the states in which it is found. Of critical concern is a subspecies of the large marble butterfly, Euchloe ausonides ausonides, which is already absent throughout much of its former range in California.
These pollinators need federal protection to survive
ESA listings would protect these species by addressing the threats they are facing and ensuring that regulatory mechanisms — which are currently lacking — are in place to protect the species in locations where they are needed most. Federal protection is especially important for the Morrison bumble bee and the large marble butterfly because they occur in several states where state wildlife agencies lack the legal authority to protect insects and are unable to address the conservation needs of these species.
We lose something precious when a species goes extinct. Morrison bumble bees and large marble butterflies are integral parts of the unique landscapes that make the western U.S. so special. Our world would be a duller place without the pleasure of watching this vibrant butterfly and bright yellow bee tumble from flower to flower.
Learn more and get involved
- Help track bee populations with the Bumble Bee Atlas program
- Learn more about the Morrison bumble bee
- Read the Xerces Society’s petition for the Morrison bumble bee
- Learn more about the large marble butterfly
- Read the Xerces Society’s petition for the large marble butterfly
As a conservation biologist for the endangered species program, Kevin’s efforts with the Xerces Society focus on protecting the hundreds of butterfly species that inhabit deserts, forests, and grasslands across the western United States. Many of these species are currently in decline or are threatened by habitat loss, insecticides, and the effects of climate change.
Saff joined Xerces in 2022 as an endangered species conservation biologist. She coordinates the State of the Bees Initiative, working with researchers and land managers to assess the status of wild bees in the western U.S. and address their conservation needs. She also works to advance conservation of butterflies and fireflies in Arizona.
