GAYLORD (AP) -- Mosquito spraying over the summer apparently caused the death of hundreds of monarch butterflies here.
On Aug. 23, hundreds of butterflies were found dead, following city-sanctioned mosquito spraying.
An investigation by the Minnesota Department of Agriculture found enough of the chemical Permethrin in tests of the butterflies to have caused their deaths, The Free Press of Mankato reported.
"That would be a sufficient amount to kill the butterflies," said Steven Mercurio, a biology professor at Minnesota State University, Mankato. "It looks like the monarchs were killed with the spray. It's a shame. I'm sure that's not what they wanted to do."
Agriculture Department officials would not release details of the investigation until it is complete.
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