Sune Boye Riis was on a bike ride with his youngest son, enjoying the sun slanting over the fields and woodlands near their home north of Copenhagen, when it suddenly occurred to him that something about the experience was amiss. Specifically, something was missing.
It was summer. He was out in the country, moving fast. But strangely, he wasn’t eating any bugs.
For a moment, Riis was transported to his childhood on the Danish island of Lolland, in the Baltic Sea. Back then, summer bike rides meant closing his mouth to cruise through thick clouds of insects, but inevitably he swallowed some anyway. When his parents took him driving, he remembered, the car’s windshield was frequently so smeared with insect carcasses that you almost couldn’t see through it. But all that seemed distant now. He couldn’t recall the last time he needed to wash bugs from his windshield; he even wondered, vaguely, whether car manufacturers had invented some fancy new coating to keep off insects. But this absence, he now realized with some alarm, seemed to be all around him. Where had all those insects gone? And when? And why hadn’t he noticed?
Riis watched his son, flying through the beautiful day, not eating bugs, and was struck by the melancholy thought that his son’s childhood would lack this particular bug-eating experience of his own. It was, he granted, an odd thing to feel nostalgic about. But he couldn’t shake a feeling of loss. “I guess it’s pretty human to think that everything was better when you were a kid,” he said. “Maybe I didn’t like it when I was on my bike and I ate all the bugs, but looking back on it, I think it’s something everybody should experience.”
I met Riis, a lanky high school science and math teacher, on a hot day in June. He was anxious about not having yet written his address for the school’s graduation ceremony that evening, but first, he had a job to do. From his garage, he retrieved a large insect net, drove to a nearby intersection and stopped to strap the net to the car’s roof. Made of white mesh, the net ran the length of his car and was held up by a tent pole at the front, tapering to a small, removable bag in back. Drivers whizzing past twisted their heads to stare. Riis eyed his parking spot nervously as he adjusted the straps of the contraption. “This is not 100 percent legal,” he said, “but I guess, for the sake of science.”
Riis had not been able to stop thinking about the missing bugs. The more he learned, the more his nostalgia gave way to worry. Insects are the vital pollinators and recyclers of ecosystems and the base of food webs everywhere. Riis was not alone in noticing their decline. In the United States, scientists recently found the population of monarch butterflies fell by 90 percent in the last 20 years, a loss of 900 million individuals; the rusty-patched bumblebee, which once lived in 28 states, dropped by 87 percent over the same period. With other, less-studied insect species, one butterfly researcher told me, “all we can do is wave our arms and say, ‘It’s not here anymore!’ ” Still, the most disquieting thing wasn’t the disappearance of certain species of insects; it was the deeper worry, shared by Riis and many others, that a whole insect world might be quietly going missing, a loss of abundance that could alter the planet in unknowable ways. “We notice the losses,” says David Wagner, an entomologist at the University of Connecticut. “It’s the diminishment that we don’t see.”
Because insects are legion, inconspicuous and hard to meaningfully track, the fear that there might be far fewer than before was more felt than documented. People noticed it by canals or in backyards or under streetlights at night — familiar places that had become unfamiliarly empty. The feeling was so common that entomologists developed a shorthand for it, named for the way many people first began to notice that they weren’t seeing as many bugs. They called it the windshield phenomenon.
To test what had been primarily a loose suspicion of wrongness, Riis and 200 other Danes were spending the month of June roaming their country’s back roads in their outfitted cars. They were part of a study conducted by the Natural History Museum of Denmark, a joint effort of the University of Copenhagen, Aarhus University and North Carolina State University. The nets would stand in for windshields as Riis and the other volunteers drove through various habitats — urban areas, forests, agricultural tracts, uncultivated open land and wetlands — hoping to quantify the disorienting sense that, as one of the study’s designers put it, “something from the past is missing from the present.”
When the investigators began planning the study in 2016, they weren’t sure if anyone would sign up. But by the time the nets were ready, a paper by an obscure German entomological society had brought the problem of insect decline into sharp focus. The German study found that, measured simply by weight, the overall abundance of flying insects in German nature reserves had decreased by 75 percent over just 27 years. If you looked at midsummer population peaks, the drop was 82 percent.
Riis learned about the study from a group of his students in one of their class projects. They must have made some kind of mistake in their citation, he thought. But they hadn’t. The study would quickly become, according to the website Altmetric, the sixth-most-discussed scientific paper of 2017. Headlines around the world warned of an “insect Armageddon.”