Not long ago, the first insect songs of summer coincided with a fresh coat of bug guts splattering your car. If you've been a driver for few decades, you may have noticed that the remains of unlucky flies, moths, and beetles don't end up on windshields as often as they once did. You may even be grateful that your vehicle is cleaner than it used to be, but the lack of bugs on the road isn't something to celebrate. The trend is known as the windshield phenomenon, and it's evidence of rapidly declining insect populations around the world.
People have been noticing fewer bugs on their windshields since the early 2000s, but until the 2010s, there was little scientific evidence to back up these anecdotal observations. Some of the earliest data on the subject comes from the Krefeld Entomological Society, which is composed mostly of amateur entomologists. They first started tracking insect populations in nature reserves throughout western Europe in the 1980s, and in 2013, they made a startling finding. Insect populations in one trapping site had declined by close to 80 percent since they last checked it in 1989. When they went back the following year, the numbers hadn't rebounded. Investigations across more than a dozen additional sites showed that the trend wasn't limited to one area.
A 2019 survey by the Kent Wildlife Trust directly linked the so-called "insect apocalypse" to what drivers are noticing (or aren't noticing) on their windshields. After following more than 650 car trips taken across the British county of Kent in the summer of 2019, they asked drivers to report the number of dead bugs that ended up on their car's license plate. They compared these numbers to the results of a similar survey from 2004, and found that the average splattered insect count had dropped by 50 percent.
Some people blamed the windshield phenomenon on the more aerodynamic designs of modern cars. To account for this, the Kent Wildlife Trust researchers found drivers with classic cars for their survey. Their findings suggest that the change over a 15-year period came from the environment—not car designs.
Multiple factors have contributed to plummeting insect populations. Bug species have been hit hard by numerous human-caused threats over the past century, including industrial farming, insecticides, and climate change. The windshield phenomenon is one effect of the crisis people may notice in their day-to-day lives. Other consequences of the insect apocalypse are much more dire. Insects don't always get as much attention from conservationists as charismatic megafauna, but they play a vital role in the world's ecosystems. Animal pollinators—such as bees, moths, beetles, and butterflies—are responsible for pollinating over a third of the planet's food crops. Our windshields may look emptier in a future with fewer insects, but so will our grocery stores.