A new study finds the Franklin bumble bee's decline began thousands of years ago due to low genetic diversity, long before modern threats.

A new study published October 20, 2025, finds the Franklin bumble bee, last seen in 2006 and native to parts of Oregon and California, likely faced long-term population decline and genetic vulnerability for thousands of years before modern human impacts. Analysis of museum specimens shows the species had extremely low genetic diversity and signs of inbreeding dating back to the glacial period, with declines worsening in recent centuries due to natural stressors like drought and wildfire. The research, using whole-genome data from 25 specimens, found little evidence linking its disappearance to pesticides or disease. The findings highlight the importance of museum collections in tracking long-term species decline and underscore the risks faced by pollinators with small ranges and fragile genetics.