Butterfly populations are rapidly declining, new study shows
Butterfly populations have dropped by 22% across 554 recorded species in the United States, according to a new study in the journal Science.
"Our national-scale findings paint the most complete -- and concerning -- picture of the status of butterflies across the country in the early 21st century," the study said.
The study, titled "Rapid butterfly declines across the United States during the 21st century," counted 12.6 million butterflies, analyzed 76,957 surveys and partnered with 35 monitoring programs to examine butterfly population trends from 2000 to 2020.
Total butterfly abundance decreased across the U.S. by 1.3% annually, leading to a cumulative 22% decline, the study said.
"These are amazing creatures that have been on the planet for a 100 million years and they connect us to that history of the planet. Fewer of them is just a tragic loss," Matt Forister, biology professor at the University of Nevada, Reno, and co-author of the study, told ABC News.
Approximately 107 butterfly species declined by more than 50% in the last 20 years, whereas only 3% increased, the study said. But, that actually is not a shock to researchers, since the declines are common across species, whereas increases are rare, the study said.
"Over the two-decade study period, 33% of individual butterfly species showed significantly declining trends in abundance," the study said.
The dip in butterfly population was seen across the country, but the Southwest was hit the hardest, which is "consistent with other findings that butterflies are disproportionately declining in arid and hot climates," the study said.
While this study's concentration was on the U.S., Forister said these results are also comparable to what researchers are seeing in Europe. He said there is less data on butterfly populations in tropical areas, but there are "suggestions that declines could be worse there because the ecosystems are more sensitive to changing precipitation patterns."
The reason for this significant drop in butterfly populations is due to several factors, one being rising temperatures and changing climates, according to the study.
"With climate change, butterfly species in North America may find the southern limits of their ranges becoming too warm while the northern limits of their range become more hospitable," the study said.
Other threats to this insect include habitat loss and pesticide use, the study said.
Researchers said there is a potential to increase the butterfly population through "habitat restoration, species-specific interventions and reducing pesticide use."
"Unlike bigger animals, insects respond to small changes," Forister told ABC News. "The most important thing people can do is use fewer pesticides in their own yards."
If action is not taken, Forister said the population of butterflies and moths will continue to decline in the coming years.
"If moth and butterfly densities continue to decrease, people will notice it in terms of less food for birds and plant pollination, meaning fewer wildflowers that people will enjoy," Forister said.
Overall, researchers said this population study serves as an "urgent need to protect butterflies from further losses."
"Expansive efforts in conservation planning and action for insects could prevent widespread future losses and create and maintain the environments in which butterflies and other at-risk species can thrive," the study said.
Monarch butterflies, for instance, are one example of a thriving species.
The population of monarch butterflies nearly doubled in population in 2024-25 versus 2023-24, according to a survey released Thursday by the World Wildlife Fund in Mexico and Mexico's National Commission of Protected Natural Areas. However, the population is still significantly below the long-term average.
This year, monarchs covered 4.42 acres, up from 2.22 acres the year before, the survey said. This increase in monarchs is directly related to improved weather conditions in 2024, but "climatic variations" in the insect's breeding areas of Canada and the U.S. as well as insecticide pose a looming threat for the winged creature.
