Bee Deaths in Minnesota

On May 7, a beekeeper in Minnesota noticed his bees were dying. I went to the beekeeper’s location a few days later and saw all the below symptoms and took samples for the beekeeper. There were bees on the ground with their legs up and twitching. There were bees that, when placed on their backs, couldn’t right themselves. There were bees on willow blossoms (the first blooming plant of the year) that should have been actively collecting pollen, but would barely lift a leg when poked or were dead. There were dead bees all over one of the few remaining snow patches and in front of the colonies. Inside the hive, the colonies looked a bit depopulated for the amount of brood and stores. There was some fresh pollen being brought in from the willows, but I didn’t see any conclusive evidence that the brood was affected.

One of the many twitching bees.

So what caused this?  It is unlikely that it was a disease or pest since colonies show symptoms at different times depending on factors such as the initial inoculation or degree of susceptibility to the specific disease, and it looked like the colonies were all affected at the same time. Plus, I don’t know of any disease or pest that would cause this aggregate and severity of symptoms. Something was affecting the bee’s movement and killing them. With the number of dead and affected bees, and from my field experience, it looked like an acute pesticide kill.

The beekeeper’s theory on why the bees were dying was that when the corn fields right next to the bee yard were being planted with corn seed coated with a neonicotinoid pesticide, the high winds blew the dust onto the willow blossoms and the bees. It is possible the bees then became exposed to the pesticide through eating the dust on the willow blossoms or by trying to groom the dust off. This theory is not unique: beekeepers in Ontario experienced losses of bees during corn planting last year, researchers documented bee losses in Indiana in 2010 and 2011, and Bayer CropScience is working on reducing the dust exposure to bees during planting.

About a week later, a second beekeeper in Minnesota reported similar issues with his bees in a yard located near cornfields that were recently planted.

In both cases, representatives from both the MN Department of Agriculture and Bayer visited the beekeepers and took pesticide samples. I went to the first case as an impartial BIP bee person, and a coworker went to the second case. At both beekeepers, we colony assessments and took samples for Varroa, Nosema, and viruses. The cause of the bee deaths at the two beekeeper operations is not yet officially confirmed. We are waiting to hear the results of the sampling. Stay tuned.

Dead bee on willow blossom.

Dead bee on willow blossom.

Corn field next to bee yard.

Corn field next to bee yard.

Dead bees on snow. There was still a patch of snow despite temperatures being in the 50-60s.

Dead bees on snow. There was still a patch of snow despite temperatures being in the 50-60s.

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About Katie Lee

I'm a part of the Midwest Bee Team based out of the University of Minnesota. I work with commercial migratory beekeepers in North Dakota and Minnesota to help them monitor pest and disease levels. Before I was on the Midwest Team, I was on the CA Bee Team working for the Northern California bee breeders. I was introduced to honey bees during my last semester as an undergrad when I took a class on social insects with Dr. Marla Spivak. Marla asked me to work in the U of MN Bee Lab over the summer, and have been enthralled with bees ever since. My main interests are bee breeding, Varroa, disease ecology, and extension work. I received both a BS in Ecology, Evolution, and Behavior and a MS in Entomology from the University of Minnesota.

6 thoughts on “Bee Deaths in Minnesota

  1. We have had the same things happening in Ontario. Field force just wiped out. The is going to be a lot of home orchards and small orchards that are going to be surprised at no apples this year. It will look like they were froze of again when there was a excellent window for pollination.
    Bill Ferguson

    • I had the privilege of going to the Ontario meeting last winter and got to hear directly from beekeepers there about the losses due to planting. There was a lot of frustration, anger, and heartache. I am sorry to hear that beekeepers are going through the same thing this year. Thank you for sharing, Bill.
      Katie

  2. Hello Katie
    Long time no see. I found you by chance while I browsed for some bee pictures. I am happy that you carried on with working with bees. Still remember when we did the bee beard in the MN State Fair back in 2005.
    Cheers

    • Hi Umberto! I remember the bee beards fondly as well. I take it you are still working with bees, too, since you were looking up pictures. Hope you are well!
      Katie

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