"Rapid butterfly declines across the United States during the 21st century" is a study published in Science. The study found that populations of butterflies across the United States are declining. In addition to dramatic declines for individual species, the study concluded that total abundance of butterflies has declined by 22% from 2000 to 2020. That means that for every five butterflies seen 20 years ago, now there are only four.
The study was completed by the Status of Butterflies in the U.S. working group, which formed to bring together all available butterfly monitoring datasets and develop a picture of the health of butterfly populations across the contiguous United States. Nearly two dozen researchers participated in the working group, including Xerces Society staff.