A team of scientists wanted to know how butterflies were doing across the United States. They gathered records of 12.6 million individual butterflies across 554 species. The records came from more than 76,000 surveys across nearly 2,500 locations.
Much of this information came from citizen scientists. Citizen scientists are everyday people who help collect scientific data, like which butterfly species they see in their local area.
The researchers found that total butterfly numbers dropped by 22% between 2000 and 2020. Collin Edwards, an ecologist with the Washington Department of Fish and Wildlife, explains what this means: “For someone who was born in 2000, one out of every five butterflies had disappeared by the time they became an adult.”
Nine of the butterfly species studied increased rather than decreased. The eastern population of the monarch butterfly doubled in 2025. This is good news, but the overall monarch butterfly population have gone down by 80%. The monarch butterfly may yet be listed on the U.S. endangered species list.
Similar declines in other insect groups have been found around the world. Scientists think that drops in the number of insects are caused by habitat loss, climate change, and pesticides.
David Brown adapted this story for Mongabay. Kids. It is based on an article by Bobby Bascomb published on Mongabay News.
