Test Results Say 25,000 Oregon Bees Poisoned to Death by Pesticide

Officials in Oregon concluded that a pesticide sprayed onto flowering trees was the cause of death of about 25,000 bumble bees in a shopping center parking lot.

Oregon's Department of Agriculture said Friday that test results conclude the application of the pesticide Safari on 55 European linden trees growing a Target parking lot was "directly related" to the death of the bees, The Associated Press reported.

The incident, which took place in Wilsonville, Ore., southwest of Portland, is being called the largest mass death of bumble bees in regional history.

"There were literally falling out of the trees," Rich Hatfield, a conservation biologist with the Portland-based Xerces Society of Invertebrate Conservation, told local news station KPTV. "To our knowledge, this is one of the largest documented bumble bee deaths in the Western U.S. It was heartbreaking to watch."

Before Friday's test results were announced, the Xerces group indicated it suspected acute pesticide poisoning as the cause of death.

KPTV reported that at least 150 bumble bee colonies were lost. Honey bees, lady bugs and other insects were also found dead at the site.

The Department of Agriculture said an investigation is underway to determine whether the application of Safari was in violation of any conservation laws.

To prevent more bee deaths, the AP reported that bee-proof netting will be placed around the European linden trees. The trees' blossoming flowers attracted the bees, which later died after exposure to the Safari pesticide.

Dying bee colonies have made headlines recently, renewing public awareness of the importance of bees to the food chain and growing seasons.

Known as "colony collapse disorder" the epidemic caused beekeepers in the United States to lose about one-third of their colonies last year. A possible cause of the endemic is the heightened use of a relatively new class of insecticides called neonicotinoids, which reduce bees' ability to learn scents, which hinders the insects' ability to find food.

Photos of the dead bees can be seen here.