Good News on Overwinter Bee Health Trends

Wednesday, May 13, 2015
Honey bee pollinating purple flower

Author:  Dick Rogers, Principal Scientist / Entomologist, Bee Health & Integrated Apiculture Research, Bayer Bee Care Center

There are still questions about how best to measure colony losses over winter months, during the spring through fall period, and on an annual basis. The USDA survey for over winter has only been conducted since 2006 and it is based on self-reporting by Beekeepers.  Over the period 2006-present, over winter losses average approximately 30 percent. Losses in cold northern states prior to the introduction of Varroa and other disorders in the mid-1980s typically were in the 0-15% range. Since then colony losses over winter have been much higher. In warm southern states, honey bees seldom need to cluster, and so they can continue brood rearing and foraging for most of the year. Therefore, it is important to define what is meant by winter and this further complicates winter loss determination and calculation.


The latest report from the USDA is good news for all who care about the health of honey bee colonies. For the second year in a row, winter losses of U.S. honey bee colonies were well below the historic average seen since these annual surveys began.  More importantly, the long-term trend of overwintering losses continues to show improvement. The reasons for success are greater awareness of factors affecting honey bee health, particularly Varroa mite, and better management, including extensive use of the highly effective Varroacide, Apivar.


This report comes shortly after the USDA released its annual Honey Report, which showed that the number of U.S. honey bee colonies grew to 2.74 million in 2014, the highest level in many years, continuing a 10-year trend of steady growth.


Summer losses are expected and common, however, because of Varroa, other disorders, queen issues, and pesticide residues in hives, especially extremely high residues of bee protecting Varroacides, beekeepers do face a challenge to keep these losses to a minimum. It is apparent that in recent years, beekeepers are doing a much better job of managing honey bees and the problems they face because colony numbers in the U.S. continue to grow. Some states, have seen substantial increases in colony numbers. Florida, for example has more than doubled the number of colonies since 2006.


Even with this good news about overwintering trends, we must continue to focus on the challenges facing bee health. Bayer CropScience is developing new solutions to the problems caused by the invasive Varroa mite and is working to tackle another major issue facing pollinators today – lack of forage – through our Feed a Bee initiative. And we recently announced our Healthy Hives 2020 research collaboration with honey bee experts to identify tangible actions to help improve the health of honey bee colonies over the next five years. Although there is much work yet to do, this report validates the efforts of many stakeholders who are working to protect bees and promote sustainable agriculture.


For more information on bee health, check out our infographic The Good News on Bee Health, and visit  





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