Becky Wheeler-Dykes, UCCE Glenn, Tehama and Colusa Counties

The 2025 almond bloom began with reports of devastating honeybee colony loss, the likes of which the industry hasn’t seen in decades. In many cases, growers and/or beekeepers scrambled to find hives to pollinate almond orchards. Project Apis m., an organization focused on supporting honeybee health and reliable pollinator populations, conducted a survey last year showing that commercial beekeepers lost an average of 62% of their bees in the ’24-’25 season. These losses equate to over $600 million to beekeepers alone. Beekeepers reported finding bees in their hives with distorted wings or dead. In some cases bees just disappeared and did not return to their hives at all.

Researchers at USDA ARS Bee Labs in Beltsville and Baton Rouge as well as Cornell University are conducting intensive research on both remaining healthy honeybees as well as hives with severe or total losses to identify which factors led to the outsized colony losses of 2025. Populations of Varroa mites, viral load in both mites and in bees, quality of bee nutrition outside of almond bloom, and pesticide residues are being studied among other aspects of honeybee health. 

The Glenn County Ag Commissioner’s office reports that beekeepers locally saw high mite populations, which contributed significantly to colony loss. It is also possible that the mites vectored viruses, compounding the negative effects. Some losses may also be attributed to application of fungicides; even a sub-lethal dose may not kill honeybees but can weaken the colony making it more vulnerable to other stressors.

Moving into the 2026 season, beekeepers are advised to be even more vigilant in monitoring mite populations in honeybee colonies. By the time a mite infestation is easily noticeable it is too severe for effective treatment with miticides. In addition to mite monitoring, providing supplemental nutrition and water sources to colonies prior to placement in orchards is shown to improve colony survival rates and long-term health. Some beekeepers have also begun testing samples of queen banks for virus loads, which may help identify and maintain healthy colony sources.

Beekeepers in California have historically been at a disadvantage compared to other states because there are so few effective miticide products registered for use in hives here. This has led to issues with black market products being smuggled into the state and used illegally; please do not do this!! Fortunately, two new products were registered by the California Department of Pesticide Regulation in 2025, expanding the mite management tool set available to California beekeepers*. VarroxSan™, a natural product claims high efficacy against even amitraz- and pyrethroid-resistant Varroa mite populations. Another new product, Norroa™, boasts a new mode of action for beekeeping, stopping the production of mite offspring. Both products are currently available in California. 

Growers can also help support honeybee health in several ways. Maintaining pollinator-friendly hedgerows or buffer zones between fields provides additional nutrition for honeybees; research has shown that this additional forage does not distract honeybees or reduce their pollination efficiency for crops. Growers should also continue to follow proper timing guidelines for fungicides, spraying fungicides in the late afternoon, evening, and night to avoid applications during bee flight and when pollen is present, and avoiding all insecticide applications when hives are present. Follow the Best Management Practices published by the Almond Board of California carefully to help optimize honey bee health in your orchards. Utilize BeeCheck though the BeeWhere California app to stay aware of the location of honeybee hives in neighboring fields. 

Honeybees are a critical component of many cropping systems, and colony health is crucial for maintaining the incredible yields and productivity California is known for. By working together, orchard crop producers and beekeepers can continue to support healthy honeybee colonies.

Thank you so much to the Glenn County Ag Commissioner’s office for their excellent insight and valuable information for this article!

*Please note that UC Cooperative Extension has not performed its own efficacy testing on these products; this information is meant to inform producers of new options and is not an endorsement of any products. As always, label is law, this is not a pesticide recommendation, and producers should always consult with licensed PCA’s prior to purchase or application of pesticides.