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© KOIN 6 NewsA close-up of one of the 25,000 bees found either dead or dying in a Target parking lot in Wilsonville, Jun 19, 2013.
Experts are investigating why 25,000 bees were found dead or dying in a parking lot at a Target store in Wilsonville.

The strange sight first caught shoppers' eyes a few days ago. It's still there Wednesday, clustered under blooming European Linden trees.

"I've never seen an incident on this scale," said Pollinator Conservation Program Director Mace Vaughan.

Experts believe this could be a poisonous species of the tree that caused them to die, or they may have been poisoned by insecticides.

Conservationists Vaughan and Rich Hatfield were in Wilsonville Wednesday,filling test tubes with samples to take back to a lab. There they'll try to confirm either theory for the bees sudden deaths.

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© KOIN 6 NewsAn expert collects some of the 25,000 bees found either dead or dying in a Target parking lot in Wilsonville, Jun 19, 2013.
"When I was here Monday it was even more dramatic than it is today," Hatfield told KOIN 6 News. "There were bees raining out of trees."

Vaughan said European Linden trees are often treated with insecticides because of the aphids that "rain down" nectar from the trees.

But there's also a chance it's not insecticide at all. Vaughan took pollen samples and will test the buds and flowers from the trees.

"We can't say for sure that it is something that they put on the tree," Hatfield said, "because these trees are European Linden trees, which have been known to be toxic to bees."

They said they hope to have an answer within a couple of days.
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© The Xerces Society for Invertebrate ConservationAbout 25,000 dead or dying bees were seen in a parking lot at the Target in Wilsonville, June 18, 2013.
"It brings it home," Hatfield said, "that we've got a lot of work to do to learn how to not harm these insects that are critical to our food supply."

Bees are critical agriculture. If there really are 25,000 to 30,000 dead bees, which is how it appears, that would be hundreds of bumblebee colonies that are now dead.