Summary:

- Butterfly populations across the United States are declining, according to new research. Scientists have found that the number of butterflies has decreased by about 35% over the past two decades.

- The decline is particularly concerning for certain species, such as the monarch butterfly, whose population has dropped by around 80% during this period. This is likely due to factors like habitat loss, pesticide use, and climate change.

- Butterflies play an important role in many ecosystems, acting as pollinators and indicators of environmental health. The decrease in their numbers is a worrying sign that ecosystems are under stress, and more needs to be done to protect these delicate creatures.