A new study by researchers at Michigan State University has concluded the butterfly population across Michigan, and the United States, is dwindling.

Bringing together the results of more than 30 long-term studies of butterfly habitats across the U.S., MSU researchers are sounding the alarm. Nick Haddad is a professor of integrative biology and one of the study’s co-authors.

“What we found, to me, was really unbelievable,” Haddad said. “About a quarter of butterflies have been lost over the last 20 years.”

Climate change, habitat loss, and most importantly, the overuse of insecticides in agriculture are thought to be the causes.