Massive Insect Population Detected Over U.S. Skies

On a typical summer day, researchers estimated about 100 trillion insects flying above the contiguous United States. This count comes from the National Oceanic and Atmospheric Administration, NOAA, and was led by Dr.

Elske Karolien Tielens at the Swiss Federal Institute for Forest, Snow and Landscape Research. Instead of catching insects in nets, the team counted radio echoes and created daily maps of insect density using radar data.

The Next Generation Weather Radar network, known as NEXRAD, includes 160 sites, where dual-polarization technology helps distinguish insects from raindrops and birds. The researchers found an average midday density of about 4.3 insects per square meter, with the thickest daytime swarms near the Gulf Coast and southern plains.

The study also built a time series from 2012 to 2021, revealing that overall daytime insect density did not show a net drop across that decade. However, 52% of radar sites measured rising insect density, while 48% reported declines, suggesting localized variations.

A significant finding was that insect density fell most in places with rising average winter temperatures, particularly at higher latitudes. Urban areas showed a greater drop in insect density, likely due to the urban heat island effect.

The study emphasizes that while radar cannot identify species, pairing radar data with other sources is crucial to understand the implications of insect population changes. These flying insects play a vital role in ecosystems by spreading pollen, controlling agricultural pests, and serving as food for various wildlife.

The findings were published in the journal Global Change Biology.