Winter Loss Survey 2011 -2012

A national survey of managed honey bee 2011-12 winter colony losses in the United States: results from the Bee Informed Partnership

IBRApaper2011-2012Published in the Journal of Apicultural Research, this survey in its sixth consecutive year, reports the winter 2011 – 2012 losses in the USA at 22.5%.


Angela M Spleen, Eugene J Lengerich, Karen Rennich, Dewey Caron, Robyn Rose, Jeff S Pettis, Mark Henson, James T Wilkes, Michael Wilson, Jennie Stitzinger, Kathleen Lee, Michael Andree, Robert Snyder and Dennis vanEngelsdorp, for the Bee Informed Partnership. 2013. A national survey of managed honey bee 2011-12 winter colony losses in the United States: results from the Bee Informed Partnership. Journal of Apicultural Research 52(2): 44-53.


Estimates of winter loss for managed honey bee (Apis mellifera) colonies are an important measure of honey bee health and productivity. We used data from 5,500 US beekeepers (5,244 backyard, 189 sideline and 67 commercial beekeepers) who responded to the April 2012 Bee Informed Partnership Winter Colony Loss Survey and calculated loss as the difference in the number of colonies between October 1, 2011 and April 1, 2012, adjusting for increases and decreases over that period. In the US, the total colony loss was 22.5% for the 2011-12 winter; 45.1% (n = 2,482) of respondents reported no colony loss. Total loss during 2011-12 was substantially lower than loss during 2010-11 (29.9%). Of the 4,484 respondents who kept bees in 2010-11 and 2011-12, 72.0% reported that the loss during 2011-12 was smaller or similar to the loss during 2010-11. There was substantial variation in total loss by state (range 6.2% to 47.7%). The average loss per beekeeping operation was 25.4%, but the average loss was not significantly different by operation type (backyard, sideline, commercial). The average self-reported acceptable loss per respondent was 13.7%; 46.8% (n = 2,259) of respondents experienced winter colony losses in excess of the average acceptable loss. Of beekeepers who reported losing at least one colony during 2011-12, the leading self-identified causes of mortality were weak condition in the fall and queen failure. Respondents who indicated poor wintering conditions, CCD, or pesticides as a leading cause of mortality suffered a higher average loss when compared to beekeepers who did not list these as potential causes.

Keywords:Honey bee, overwinter, mortality, colony losses, USA, 2011-12

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Written By: The Bee Informed Team

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The Bee Informed Partnership is a collaboration of efforts across the country from some of the leading research labs and universities in agriculture and science to better understand honey bee declines in the United States. Supported by the United States Department of Agriculture and the National Institute of Food and Agriculture, we’re working with beekeepers to better understand how we can keep healthier bees. The key to our success is the true partnership we maintain across a wide range of disciplines including traditional honey bee science, economics, statistics, and medical research that makes all these tools available to this important research. And just as important as the tools are the people. We not only have the leading researchers in the honey bee industry, we also have advisory boards from the commercial beekeeping industries, almond and other commercial growers, as well as naturalists and conservationists from across the country.