25,000 Dead Bees Found in Parking Lot Likely Killed by Pesticide

Why did 25,000 bumble bees suddenly drop dead in a Target parking lot in Oregon?

That’s the question insect conservationists with the Portland-based Xerces Society are trying to answer.

The bees were found under a dozens of European linden trees Monday in Wilsonville, according to Oregon Public Broadcasting's website, raising the question of whether the insects were killed by a poisonous species of linden tree or by pesticide poisoning.

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Bumble bees play a crucial role in pollinating berries, flowers and other plants. So do honey bees, whose numbers have been dramatically declining since 2006.

The bees "were literally falling out of the trees," said Rich Hatfield, a Xerces Society conservation biologist. "To our knowledge this is one of the largest documented bumble bee deaths in the Western U.S. It was heartbreaking to watch."

The Xerces Society has contacted the Oregon Department of Agriculture, which has collected samples of the bees and foliage from the trees. The agency will be working to determine whether pesticides were used at the site.

Hatfield said the dead bumblebees represent a loss of more than 150 colonies. He also noted dead honeybees, lady bird beetles and other insects.

"If the trees are indeed toxic, they should be cut down and replaced by something that will provide non-toxic pollen and nectar for bees," said Scott Hoffman Black, executive director of the Xerces Society. "On the other hand, if pesticides are the cause, we need to spotlight this real-world lesson in the harm these toxic chemicals are causing to beneficial insects."

A primary focus of the Agriculture Department's preliminary investigation is a pesticide called Safari that apparently was applied in the area last Saturday to control aphids, said Dale Mitchell, program manager in the Agriculture Department's pesticide compliance and enforcement section.

Pesticides have been implicated in bee deaths before, and some of them have been banned in Europe. Safari is part of a family of pesticides called neonicotinoids that are considered acutely toxic to pollinators.

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Mitchell noted that approved pesticide products carry very specific hazard labels.

Bee and vegetation samples were taken for testing to confirm what was responsible for the kill, Mitchell said. His investigation will look at any potential pesticide use in the vicinity.

"Honey bees and bumble bees were arriving as we were there, and bees are still dying," Hilburn said in a telephone interview Wednesday evening.