Overview

• Analysis of more than 4.3 million observations shows zero increases in species richness or abundance among 136 butterfly species across the Midwestern United States.
• Average county richness fell from 10 to 9 species and individual counts dropped from 100 to 60, marking 10% and 40% declines respectively.
• Statistically significant declines were detected in 59 species, including widespread losses among both common butterflies like monarchs and rare specialist species.
• Researchers note that the 32-year study period overlaps with rising neonicotinoid use and climate-driven weather shifts, though direct drivers were not assessed.
• Conservationists are now using these high-resolution, long-term trends to develop targeted protection plans, update pesticide policies and prioritize habitat restoration.