Fifty thousand bumblebees will be honored at a memorial Sunday in the same shopping center parking lot southwest of the Portland, Oregon, where most of the insects died earlier this month.

Rozzell Medina, of Portland, said on a Facebook page that the event will "memorialize these fallen lifeforms and talk about the plight of the bees and their importance to life on Earth," The Oregonian reported.

The state Department of Agriculture said June 21 that tests on bees and foliage showed the deaths are "directly related to a pesticide application on linden trees" that was meant to control aphids.

It said an investigation is under way to see if the application of the pesticide Safari, done last Saturday, violated the law.

The Agriculture Department, the City of Wilsonville, neighboring towns and some local landscape contractors have covered the sprayed trees with netting in an effort to prevent further insect deaths, The Oregonian reported.

The Xerces Society for Invertebrate Conservation has upped its estimate of the bee kill to 50,000. Spokesman Scott Black calls that a very conservative number.

The Associated Press contributed to this report.

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