Monarch Butterfly

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National Fish and Wildlife Foundation

The future of Illinois' official state insect is in doubt.

The Monarch butterfly has seen its population decline by 80 percent over the past ten years, putting it at risk of becoming endangered.

The decline of the monarch butterfly population has led researchers to look for reasons why. 

A popular theory is the loss of milkweed, the only plant on which monarch larvae feed.  But a study from the Illinois Natural History Survey at the University of Illinois indicates that's not the sole culprit.