CHICAGO (WBBM) – Chicago’s Peggy Notebaert Nature Museum is trying to unravel the mystery of millions of monarch butterflies that are unaccounted for and may be missing.

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Biology Curator Douglas Taran says the past summer was a bumper crop for the orange and black butterflies around Chicago and throughout the Great Lakes.

Monarchs are–like many birds–migrating creatures that fly thousands of miles between their summer and winter habitats.

But Taran says butterfly counters didn’t see the same large numbers of monarchs migrating through Texas on their way to their winter refuge in canyon forests 100 miles west of Mexico City.

Taran says best scenario is that the monarchs just went uncounted, possibly drifted on westerly winds out over the Gulf of Mexico, and then flew south into their winter homes as usual.  Or they may have flown higher and escaped notice of butterfly monitors en route.

The worst case scenario is that butterflies died off for some reason during the migration and before they began funneling through Texas.

With the annual monarch census now starting in Mexico, Taran is anxiously awaiting word on why or whether monarch numbers dropped so dramatically after a bumper growing season in the upper Midwest.

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