Why So Many So Late?

Observers in the north are seeing recently-emerged adults. Warm fall temperatures have given these butterflies extra time to complete their life cycle. Had it not been so warm, many eggs, larvae and chrysalids would not have had time to become adult butterflies. Will these butterflies make it to Mexico? Their challenge will be to beat the upcoming cold - and to find late-blooming flowers with enough nectar. This year’s late migration shows how climate change can affect monarchs. Scientists watch for ecological mismatch like this, where the timing of natural events is out of sync.