Expert Explains Why Butterflies Seem To Be Dying En Masse Along Lake

Mike Krauser
October 08, 2019 - 5:26 pm

Dead Monarch butterflies lie dead on a small stack February 15, 2002 at the protected Santuary of Chincua at Michoacan State, Mexico. Recent freezing weather in Mexico has caused the death of thousands of Monarch Butterflies. (Photo by Getty Images)

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CHICAGO (WBBM NEWSRADIO) -- Dead monarch butterflies spotted on local beaches have caused some concern, but an expert says it’s natural. 

The monarchs we’re seeing now migrated north from Texas in the spring and are trying to head to Mexico, where they would spend the winter before returning to Texas in the spring. They’ll lay eggs in Texas, die, and the cycle will repeat.

“We’ve had a particularly large migration this year, which is great,” says Doug Taron, chief curator at the Peggy Notebaert Nature Museum. “Butterflies, as they’re flying south, tend to accumulate at the lakefront.

“Westerly, prevailing winds pushed them towards the lake, but they don’t want to fly over the water. If you get a rain event, or something like that, you get a bunch of them falling out on the beach.”

Taron is part of the Illinois Butterfly Monitoring Network. The organization has recorded the fourth-highest number of monarchs in Northern Illinois since the count started in the late-1980s.