Bumble Bee Die-Off Under Investigation in Virginia

Pollinator week is set at an ideal time in mid-June. People around the country are enjoying the profusion of pollinators visiting the flowering plants in and around their neighborhoods. Unfortunately, bee kill incidents have marred what should be a week of celebration. Here in my own state of Oregon, between 2013 – 2015, there were seven bumble bee kills reported after ornamental trees were treated with neonicotinoid insecticides. All of these incidents occurred during or within a few days of pollinator week. The largest of these incidents, which occurred in Wilsonville Oregon, knocked out hundreds of wild bumble bee colonies killing an estimated 50,000 bees and shocking the nation.


Dozens of bumble bees lay dying in this Wilsonville, OR parking lot in June, 2013. The bees were exposed to pesticides applied to the adjacent trees. Photo: The Xerces Society/Rich Hatfield


The incidents follow the same pattern: Linden trees (Tilia spp., a favorite for many pollinators) were treated with neonicotinoid insecticides to kill nuisance aphids that release sticky honeydew. Once the trees bloomed, visiting bees were found under the trees dead and dying. In all but one incident, applicators adhered to the pesticide labels. That is a key point since the label is the law and it is supposedly how we protect against “unreasonable adverse affects”.

The Xerces Society worked hand in hand with the Oregon Department of Agriculture (ODA) to respond to the individual events and to find a solution to avoid future incidents. After conducting a thorough review of the science, ODA established a new rule which halts the use of four highly-toxic, long-lived neonicotinoids on Tilia trees. Since the rule went into effect, Xerces has not received any calls reporting bumble bees dying under Tilia trees… until this past week.

Late Friday afternoon Xerces was contacted about bumble bees falling from Tilia trees in Virginia. While the incident is still under investigation, this bee kill seems to follow the same pattern as Oregon’s incidents. Early reports from the Home Owners Association representative who has been in contact with the arborist, are that the trees were most likely treated by soil injection in late March to prevent aphids from infesting the tree. Now that the trees are in bloom, thousands of visiting bumble bees are being found dead and dying below the trees.

Fortunately, people care about bees. The same concerned representative of the Home Owners Association that spoke with the arborist also contacted the Virginia Department of Agriculture and Consumer Services (VDACS) to investigate. Late that same Friday afternoon a VDACS investigator came and took samples of the bees and blossoms to determine if and how pesticides might have been involved.


Linden trees are visited by many pollinators when in bloom and are frequented by bumble bees. In the Wilsonville case, the trees were netted to avoid further casualties. Photos: The Xerces Society/Rich Hatfield


Receiving the updates of dead bees remind me of walking under Tilia trees in Eugene, Oregon while bumble bees fell around me. Still, I am hopeful a positive outcome might be had from this terrible occurrence. If the investigation in Virginia has the same results as Oregon, and harmful levels of insecticides are found in flowers from legal application methods, Virginia and, ultimately, the US Environmental Protection Agency should step up to stop these easily avoidable bee kills.

No matter the result of the Virginia investigation we should ask ourselves what more we can do for our declining pollinator populations. Should we be using highly-toxic insecticides on bee-attractive trees simply to kill an annoying pest – one that doesn’t threaten human health or the health of the tree?  In my mind the answer is a resounding no.

This week should inspire us to be a part of the solution. At home, we can plant more flowers and choose not to use harmful pesticides. Regulators can also step back and reassess their actions. I for one hope that Virginia and other states follow Oregon’s lead. Such a change would be a great victory for pollinators and the people who depend upon them.

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