AUBURN, ALA. — US beekeepers have suffered their highest colony losses in more than a decade, according to the annual US Beekeeping Survey, and a familiar pest is largely to blame.

More than 55% of managed bee colonies were lost in 2023-24, the most since the 2010-11 beekeeping season, according to the survey released Dec. 5. That’s nearly 15 percentage points higher than the 13-year average annual loss rate of 40%.

“Assessment of commercial beekeeping colonies going into the 2023-24 winter revealed a significant uptick in varroa mites late in the fall compared to previous years, warning beekeepers of potentially high losses,” said Anne Marie Fauvel, program director for the American Honey Producers Association.

Varroa mites are external parasitic pests that prey on western honeybee and Asian honeybee populations, attaching themselves to the bodies of bees and reproducing within their colonies. Without treatment, bee colonies affected by varroa mites generally collapse in two to three seasons, according to US Department of Agriculture data.

“Varroa mites are always a problem,” added Samantha Brunner, North Dakota state bee inspector. “Also, if honey flow lasts longer than expected, it could delay treatment and cause things to snowball, leading to higher losses. In all likelihood, there were a variety of factors such as these.”

The USDA’s annual colony loss report found varroa mites were the No. 1 stressor for bee colonies last year, and through the first two quarters of 2024, nearly half of US bee colonies were affected by the mites. South Dakota had the highest incidence at 70%, followed by Alabama (62%) and Texas (60%).

While varroa mites have been seen as major contributors to colony collapse disorder (CCD), the USDA has found overall CCD rates have declined sharply so far this year. From January through March, 70,650 US bee colonies were lost to CCD, a 34% decrease from the same period in 2023. Overall, 332,570 US bee colonies were lost to CCD last year, compared with 133,410 through the first six months of 2024. If that trend holds, nationwide CCD rates will decline about 20% year over year.

Since 1986, the earliest year USDA data is available, total US honeybee colonies peaked at 3.5 million in 1989, before declining steadily in subsequent decades. By 2008, the United States had just 2.3 million colonies. That number grew to about 2.5 million last year.

Total US honey production, meanwhile, peaked at 235 million lbs (106,818 tons) in 1987. It reached a record low of 125 million lbs (56,818 tons) in 2022 before improving to 139 million lbs (69,500 tons) in 2023. Since 2000, nearly 40% of domestic honey production has evaporated, while domestic consumption has grown to 550 million lbs (275,000 tons) annually. Imports account for about 80% of US honey consumption, led by India, Argentina, Brazil and Vietnam.

“Building on the large dataset already developed by the Bee Informed Partnership, University of Maryland, and Auburn University, this year’s survey, in partnership with the Apiary Inspectors of America, will allow us to keep studying important drivers of honeybee colony loss, like varroa management and weather,” said Geoff Williams, an associate professor at Auburn University and director of the Auburn Bee Lab.

Williams noted the latest surge in colony losses was driven largely by losses among commercial beekeepers managing more than 500 colonies, a reversal of the survey’s usual findings.

“Backyard beekeepers traditionally experience greater losses than commercial beekeepers, but this time around it was flipped,” Williams said. “The commercial beekeepers lost more.”