This week, a number of dead monarch butterflies were found along the lakefront. The sight alarmed some members of the public who spotted the insects.
But one local expert says it’s par for the course as the butterflies retreat south for the winter.
“These same butterflies that emerge in northeastern North America at the end of the summertime will fly down to the mountains about 100 miles east of Mexico City,” said Doug Taron, chief curator at the Peggy Notebaert Nature Museum. “Some of the butterflies will fly over 2,000 miles to get there.”
This year’s migration was particularly large, Taron said. And those monarchs found dead near Foster Avenue Beach are a small percentage of the overall population.
The butterflies’ seasonal journey is difficult.
“The prevailing westerly winds tend to blow monarchs migrating in Wisconsin and Illinois over to the shore of Lake Michigan,” Taron said. “They don’t want to cross the lake. They use the lake as a migration corridor, and larger numbers of them will be flying south right along the lakeshore. A percentage of those land, exhausted on the beach or don’t make it all the way across and land in the water and then wash up on the beach.”