In the face of colony collapse, some beekeepers are foregoing insecticides and opting instead to breed bees with mite-resistant behaviors.
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In the face of colony collapse, some beekeepers are foregoing insecticides and opting instead to breed bees with mite-resistant behaviors.
June 11, 2025
Worker bees move across brood cells, tending to the new larvae within. (Photo credit: Denise Fletcher)
July 16, 2025 Update: A new study published last month by the U.S. Department of Agriculture (USDA) discovered that varroa mites had spread a bee virus to nearly all colonies tested at six large commercial beekeeping operations that send hives across the U.S. The research paper also found that all the mites screened had developed resistance to amitraz—the pesticide used to get rid of them—after years of heavy use.
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In April, clutching the steering wheel of my old truck, I rattled down narrow dirt roads in southern West Virginia with my mother. We were on a mission to secure a nucleus colony, or “nuc,” of locally bred honey bees from the “bee monks” of Holy Cross Monastery.
The monastery rises like a fairytale castle out of the wooded hills, with its crisp white sides and dark green domes. Just beyond it lies a sunny hillside dotted with humming stacks of hives. Though they may seem perfectly ordinary, something special is going on within them.
Were you to peek inside, you might spot a returning worker bee stamp its legs and rhythmically sway from side to side, inviting another bee to groom it. Another worker might take up the offer by roughly cleaning the dancing bee with her mandibles and forelegs, removing pathogens, debris, and parasites like the Varroa destructor mite, which feeds on honey bee brood, or the immature bees still developing in cells, as well as adult worker bees. Since 2000, the monks have been breeding the bees at the monastery to resist this mite, which is among the many dire threats facing U.S. honey bees.
The accidental introduction of Varroa destructor to North America in the 1980s has been a disaster for western honey bees.
Starting in 2006, beekeepers have reported an average annual loss of 30 percent of their colonies with no apparent cause—a phenomenon that has come to be known as colony collapse disorder. The situation has gotten much worse in recent years: A survey released this April by the Honey Bee Health Coalition confirmed the loss of 1.1 million U.S. honey bee colonies between June 2024 and February 2025, with commercial beekeepers sustaining an average loss of 62 percent.
The loss is likely caused by a combination of factors, including pesticide exposure, climate change, habitat and food source loss, bacterial diseases like American foulbrood, and parasites like Varroa mites—which have been found to develop resistance to amitraz, the insecticide most commonly used to treat them.
If you were to look closely at an infected worker bee, you could probably spot these dark brown or reddish mites, flattened oval-shaped insects about the size of a pinhead. As the mites feed, they weaken the bee and make it more susceptible to disease. A high number of mites will weaken the entire colony.
While there are some treatments for Varroa mites, some brave beekeepers—like the monks at Holy Cross—are taking a new approach by abstaining from treatment. By not treating for mites and letting susceptible colonies die off, they hope to breed new, stronger generations of bees that can reduce mite numbers on their own through behaviors like grooming and taking care of each other.
Beekeepers across the United States rely on western or European honey bees (Apis mellifera), of which there are a number of strains, including Italian, Carniolan, Russian, and Buckfast bees. These bees populate the backyard hives of hobbyist beekeepers, honey production apiaries of small farms, and wild colonies in rotten trees.
They’re also essential for the vast pollination operations, made up of thousands of hives, that beekeepers rent to farms across the United States to support crops like grapes, almonds, strawberries, kiwis, and melons. The continued loss of these bees would lead to disruptions in the food supply worldwide.
The mites we now find plaguing western honey bees are native to Asia, where they co-evolved alongside the Asian honey bees (Apis cerana). Thanks to a long period of coevolution, Asian honey bees have developed strategies to keep mite populations in check. For example, Asian nurse bees can detect and seal up infected cells, entombing the mites. Unfortunately, western honey bees evolved in Europe before colonists brought them to North America. Without any mite pressure, they had no reason to evolve defenses.
The accidental introduction of Varroa destructor to North America in the 1980s has been a disaster for western honey bees.
A Varroa destructor, perched on a beekeeper’s fingertip.
While it’s difficult to assess the full impact of the mites, we know that wild populations of honey bees experienced major crashes and even disappeared from certain areas. Today, 90 percent of the colonies sampled by the APHIS National Honey Bee Disease Survey have Varroa mites.
In the years following the introduction of Varroa, scientists, beekeepers, and agriculture experts scrambled to fight the mites. They developed both natural and synthetic treatments, but most commercial beekeepers since the late 1980s have relied on amitraz, which kills lice, ticks, and mites.
Unfortunately, amitraz is a potent neurotoxin for other insects too, and because it can have detrimental effects on egg-laying and bee development, beekeepers must walk a tightrope between treating enough to kill the mites and not harming too many bees in a colony.
Another challenge to amitraz use is insecticide resistance: Each season, the mites that survive exposure pass their genes to the next generation, eventually creating a population of mites not affected by the treatment.
This year, the EPA registered a new pesticide for mite control with two more on the way. Only time will tell if these products offer safer, more long-term alternatives to amitraz.
Since the mid 1990s, researchers and beekeepers have observed mite resistance in several wild and domestic bee populations. More recently, scientists have linked it to a set of behaviors collectively known as Varroa Sensitive Hygiene, or VSH. These behaviors include cleaning and removing larvae in parasitized cells, removing adult mites from the bodies of adult bees with a grooming behavior, and uncapping and recapping infested brood cells, which may disrupt the mites’ life cycle.
While Asian honey bees had hundreds of years to adapt to the mites, scientists have found that it may not take that long for bees to develop natural resistance behaviors. A decade ago, a group of scientists started taking a hard look at samples of wild bees collected around Ithaca, New York from 1977 to 2010, a period which conveniently spans the introduction of Varroa to the U.S.
They found that when Varroa was first introduced, the population of wild bees plummeted, but they didn’t go extinct. In response to this new pressure, the bees adapted. The scientists found that by 2010, these wild honey bees exhibited 232 genetic changes.
While scientists don’t fully understand the consequences of these changes, they were able to determine that about half were related to pupal development, a key period for the mites and the bees, because the mites breed in the brood cells that house the bee larvae as they develop into pupae. Scientists also found genetic changes related to bee dopamine receptors, body shape, and wing size. While these adaptations require further research, they have hypothesized that the changes in dopamine receptors encouraged grooming.
Many beekeepers are now watching their hives closely for these behaviors. The bee monks in West Virginia, for instance, open their hives once a month from May to October to do Varroa mite counts. By observing the bees, they can sometimes catch glimpses of VSH behaviors like grooming in action, but the real data comes from the mite counts.
In Vermont, Troy Hall of Hall Apiaries opens hives in the field during the summer and examines the pupae to measure VSH. He looks at the percentage of reproductive mites—those with daughter mites—and non-reproductive mites in the brood. Because colonies with VSH traits will remove pupae with reproductive mites and ignore non-reproductive mites, the higher the percentage of infected cells with non-reproductive mites, the more VSH traits the colony displays. Hall uses the colonies with high levels of VSH traits to breed new generations of bees for his apiary.
Hall began raising mite-resistant bees about 20 years ago and was skeptical of traditional treatments like amitraz from the start. “Early on,” he said, “I decided it would be best to develop systems of management that would be good for the future.”
The earlier years were tough. When he started with around 100 hives, there wasn’t much advice available for beekeepers looking to take on this journey. “We had no real way to measure resistance,” Hall said. “The only logical way was just to withhold treatment. It was simple: Those who survived were bred. No one was sharing methods or success. At the time, we all had to be our own trailblazers.”
For many smaller beekeepers, that’s still their breeding method. In Pennsylvania, Micheal K. Scott, who goes by The Renaissance Beekeeper, doesn’t monitor for VSH, but he does carefully select his bees. His most successful bee yard started with a few untreated hives that survived when all the others failed. He still adds to this bee yard, but only with colonies that survive into their second season.
Denise Fletcher, a hobbyist beekeeper and retired operating nurse in Kentucky, believes that one of the keys to good beekeeping is being open-minded. After researching VSH, she’s spotted signs of it in her own hives, but these days she says, “I’m pretty hands off.” Fletcher isn’t up for the kind of frequent monitoring that Hall and the Bee Monks perform. Instead, she is experimenting with thyme, oregano, and wintergreen essential oil, which may be effective in killing Varroa mites and reducing disease issues.
Hall is the first to admit that this style of beekeeping is tough. He says it comes with a significant financial investment, plenty of labor, and a steep learning curve. But it’s worth it, he says. His goal is “to prove to people it’s possible to have a small family farm and live peacefully” without too many inputs.
Still, many beekeepers and experts remain skeptical about breeding resistant bees. Some of the traits that help wild hives survive, like an increase in swarming—when part of the colony leaves to start a new hive—aren’t ideal for honey production. Swarming breaks the bee’s brood cycle and interrupts the mite’s breeding cycle, resulting in fewer mites, but it also reduces a hive’s population and honey production. If this is one of the key ways wild bees survive the mites, it’s unlikely to help beekeepers.
Breeding mite-resistant bees may come with other challenges and drawbacks as well. Honey bee queens and drones have large mating ranges, and if a non-resistant population is within flight range, the mixing of genes could delay or prevent success.
Additionally, the “live and let die” approach of allowing weak colonies to collapse could turn those colonies into targets that other, healthy hives might rob for honey, the primary food source for an overwintering colony. This contact could spread mites and pathogens back to an otherwise healthy colony.
Despite the challenges, some scientists, like Varroa and honey bee expert Dr. Melissa Oddie, think this method is worth the cost. Working with Norwegian beekeepers, Oddie studied what happens when you stop treating honey bees for Varroa mites.
“It’s like an arms race,” she said. The bees that survive quickly build up defenses, or behaviors, faster than the Varroa mites can kill the colony. Rather than being a major threat, the mites become a minor annoyance.
When beekeepers stick with it and only breed from the colonies that survive, Oddie found it takes just four years for the bees to adapt. A study released in December 2024 supports this technique, finding that “many Varroa resistance traits have a genetic determinism.” This confirms that VSH can be passed from one generation of honey bees to the next.
Still, the years required to create mite-resistant colonies can be long time for beekeepers working to make ends meet. Hall said his losses were substantial over the first several seasons. He estimates that as Varroa became prevalent, he went from a 20 percent loss each winter to 50 or 60 percent.
While Hall’s early losses may sound scary, they correspond with the current dramatic losses among commercial beekeepers, according to April’s Honey Bee Health Coalition survey.
Thankfully for Hall, his initial sacrifice may have paid off. Despite increased losses nationwide, Hall says he had about a 30 percent loss each winter for the last three years— well below the national average.
Being able to breed his own mite-resistant bees is crucial to his success, he said. He plans to go into each winter with double the colonies he actually needs in case of significant losses.
Adam Davidson, a small Kentucky farmer raising Dexter cattle and honey bees, shared a similar experience. He says that modern practices encourage beekeepers to buy packages of bees and restock each year. “The sustainable approach is to use swarms [from your own hives] and create enough hives this year to make up for your losses next season.”
Davidson says he doesn’t actually see himself as aligned with the buzzword “sustainable” that’s tossed around; he just wants to “provide for himself and his animals without input from Big Ag.”
He started beekeeping with a wild swarm of bees. He says those wild bees showed him that it must be possible to raise bees without mite treatments even when everyone was saying it wouldn’t work. Now he sees breeding his own bees as the only way forward.
We know that breeding for mite resistance has been working for some small to medium-sized commercial honey apiaries and hobbyist beekeepers. However, doubling the number of hives they care for may not be feasible for many of the enormous pollination operations that keep thousands or even tens of thousands of hives in support of the almond orchards in California, strawberry farms in Florida, and other pollination-dependent crops.
For larger operations or beekeepers worried about the initial loss of bees, Oddie recommends taking a hybrid approach. She says of treatments like amitraz, “don’t stop cold turkey.” Instead, she advises beekeepers to check mite levels three times per year and treat the colonies that exceed a certain threshold. For these poor-performing colonies, she says, “either remove them far enough from your breeding apiary that they cannot contribute drones, or else castrate them by drone cutting.”
Slowly reducing treatments, she said, can help identify successful colonies and promote mite resistance while still maintaining hives for honey production and pollination.
Whatever method you use, and regardless of whether you’re a commercial beekeeper or a hobbyist, Oddie believes that it’s essential to be flexible—and to share your experience, so that beekeepers like Hall, Davidson, Scott, and Fletcher don’t have to go it alone, like they have in the past. Online beekeeping groups and local breeding programs are great resources. “One thing is for certain,” she says, “if we keep open minds and work together, I think we can achieve anything.”
As I stand next to my truck, a monk in a black habit and bee veil gently places the nuc of mite-resistant bees I ordered into the bed. It’s my second attempt at keeping honey bees, after my first hive from Georgia failed to make it through a single winter. Like many hobbyist beekeepers, I don’t know if Varroa ultimately led to their collapse, but it’s not hard to imagine that the mites played a role.
U.S. honey bees are still in dire straits, and only time will tell if breeding mite-resistant bees will have a meaningful impact on colony collapse. But the buzzing nuc in the truck feels like a warm spark of hope.
July 30, 2025
From Oklahoma to D.C., a food activist works to ensure that communities can protect their food systems and their future.
This is a wonderful article!
Thank you.