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If you wandered through a Midwestern meadow in 1992 to look for butterflies, the odds are good you would have seen many more than if you returned to the same meadow today.
It’s no secret of course that much of the order Lepidoptera—which includes butterflies, moths and skippers—is in trouble. But new information emerges when scientists can get their hands on more than 4.3 million butterfly observations taken over more than three decades. The massive dataset, collected across the United States Midwest, contained counts of more than 136 different species, including monarchs and swallowtails. The outlook for these pollinators is not sunny.
“We expected to find that at least some species had done well over the past 32 years,” said Wendy Leuenberger, a Ph.D. candidate at Michigan State University, in a statement. This was not the case. Not one of the species grew in population numbers—and 43 percent of the species declined in that period. “While most of the common species like monarchs and cabbage whites are still present, you wouldn’t see nearly as many of them as in 1992. You’re less likely to spot rare species as well,” she said.
The findings were made possible by massive amounts of volunteer hours—some 90,000—and strict protocols maintained over the years so that the data could be compared across decades, said the lead study author, Elise Zipkin, director of Michigan State University’s Ecology, Evolution, and Behavior Program. The paper was published this week in Proceedings of the National Academy of Sciences.
Butterflies, along with moths, are key pollinators and are sensitive to environmental disruptions, including climate change, pesticides, and habitat destruction. Considering the substantial shift in the numbers of these charismatic animals, Leuenberger added: “These are all changes that have occurred in my lifetime, which is humbling.”
The efforts to track and better understand butterfly populations continue—often similarly underpinned by help from community volunteers. We’ve collected a list of opportunities to contribute to science and ecology by counting butterflies. Read more here. 
Lead image: Natalja Petuhova / Shutterstock
