Windshield phenomenon

The windshield phenomenon refers to the noticeable drop in the number of dead insects that stick to the windshields and front bumpers of cars since the early 2000s. People have observed that their car windows are much cleaner now compared to years past, and this change gives us important clues about the natural world.

Scientists believe this phenomenon is linked to a bigger issue — a global decrease of insect populations. Many insect species have been declining, and this reduction is thought to be caused by human activities. One major factor is the use of pesticides in farming, which can harm insects.

The windshield phenomenon serves as a simple yet powerful way for people to understand how human actions affect the environment. By noticing fewer bugs on car windows, we can become more aware of the health of ecosystems and the need to protect insect populations, which are vital for pollination and balancing nature.

Background

Since the early 2000s, drivers have noticed that their windshields don’t get covered in as many insects after long drives. In 2016, Canadian naturalist John Acorn talked about how people were sharing this idea online, but he wondered if we can really learn about insect numbers just by looking at windshields. The topic became very popular in 2017 when big news outlets and other media talked about how fewer insects are being seen over the past few decades. Entomologists also mentioned that they don’t need to clean their windshields as often anymore.

Studies

A 20-year study in Denmark measured the number of dead insects on car windshields from 1997 to 2017 and found an 80% decrease. Similar studies in the United Kingdom began in 2004, when the Royal Society for the Protection of Birds asked drivers to place sticky film on their number plates. They found one insect every 8 kilometers driven.

Later studies in 2019 and 2021 by the Kent Wildlife Trust and Buglife showed even fewer insects hitting cars. Modern cars with sleeker shapes were found to hit more insects than older, boxier cars. By 2025, the number of flying insects hitting cars in Kent had dropped by 66% since 2021.