Winter bee deaths hit decade high, challenging beekeepers

 Entering this spring, beekeepers will be tasked with rebounding from the worst winter in over a decade for winter bee mortality.

A nonprofit organization, called Project Apis m., surveyed more than 700 U.S. commercial beekeepers and found they lost 62% of their colonies between July 2024 and February 2025.

The U.S. Department of Agriculture’s National Agricultural Statistics Service, or NASS, estimated more than 2.5 million hives were managed by beekeepers in the U.S. in 2024. Of that, 29,000 colonies of bees in Mississippi produced honey last year, not including colonies owned by northern U.S. beekeepers who winter their bees in the state.

Jeff Harris, apiculture specialist with the Mississippi State University (MSU) Extension Service, said varroa mites, which are the primary killers of honeybees, have become more physically resilient since they were first reported in the U.S. nearly 40 years ago, which has led to the increased mortality numbers.

“It seems to be the typical story of a pest becoming resistant to the insecticide used to control it,” Harris said. “The insecticide is amitraz, and it is usually used in the form of a no-pest strip that is hung inside beehives to kill mites. We noticed that amitraz was no longer killing varroa mites here in Starkville beginning late summer 2024.”

Harris said what makes varroa mites so lethal to honeybees is the viruses they transmit to them – most commonly the Deformed Wing Virus. Mites feed on the bees’ bodies, mainly in the pupal stage during development into adult bees.

To properly combat varroa mites, commercial beekeepers need more varieties of insecticides in their arsenal that are deemed safe for honeybees, Harris said.

“These insecticides need different modes of action, and the beekeepers need to rotate and use different insecticides over time to slow down the development of resistance to any one of the chemicals,” he said.

Hobbyist beekeepers who do not want to introduce insecticides to their hives have possible alternatives that are too labor-intensive and impractical for a commercial beekeeper with thousands of colonies. One non-chemical method, known as drone trapping, involves colonies making drones (male bees) on special combs from March to May.

Once the drones are produced, Harris said the drone brood is about nine times more attractive than the worker brood in the hive.

High mortality of beehives can reduce the number of colonies available for the managed pollination of crops that need insect pollination. Without enough colonies, the growers risk not getting the maximum number of pollinated blossoms, resulting in a dramatic reduction in crop yield.

While many beekeepers in Mississippi replace dead colonies with new colonies that they can make by budding off new colonies from the strong ones that survived a winter, even the most skilled practitioners have been stretched to their practical limits with high annual losses.

“Before the 60-70% loss this winter, our beekeepers saw 35-40% losses annually over the last decade,” Harris said. “Beekeepers can replace colonies, but it costs them to do so. The profit margins are small, and the effort to replace colonies of bees that die is becoming unsustainable. It is especially tough when cheaper honey from foreign suppliers tends to hold down the price of our domestic honey.”