Where Have the Insects Gone?

When was the last time you were in a car when—SPLAT!—an insect flew into the windshield? If you can’t remember, you’re not alone. Insect fans and researchers around the world have noticed fewer run-ins with the flying creatures. This phenomenon, called the Windshield Effect, made people wonder how many insects were left.

Thanks to a 27-year-long study, entomologists and citizen scientists in Germany found that a staggering 75 percent of the country’s flying insects have vanished. Certain species of butterflies and moths are well studied, but it’s hard to keep track of how insects overall are doing. The number of insects is just too massive to count.

You’re in a car when—SPLAT!—an insect flies into the windshield. When was the last time that happened to you? If you can’t remember, you’re not alone. Insect fans and scientists around the world have noticed fewer bugs while driving. They called the phenomenon the Windshield Effect. It made people wonder how many insects were left.

Entomologists and citizen scientists in Germany conducted a 27-year-long study. They found that an alarming 75 percent of the country’s flying insects have disappeared.

Certain species of butterflies and moths are well studied. But it’s hard to keep track of how insects are doing overall. The total number of insects is enormous. That makes them very difficult to count. 

But the Windshield Effect alarmed members of the Krefeld Entomological Society in Germany. “The original aim was simply to get a good idea of the diversity of insects in Germany,” says Hans de Kroon, an ecologist at Radboud University in the Netherlands who helped with the study.

Starting in 1989, researchers used Malaise traps to collect insects. These traps have a tentlike net that funnels insects into collection bottles. The trapped insects serve as a sample of the area’s overall insect volume and diversity. Volunteers set out and checked these traps for entire seasons for the next two decades. They were extremely careful to put the traps back in the exact same spot each year.  

But the Windshield Effect alarmed a group of insect fans in Germany. They decided to try to count the flying creatures. “The original aim was simply to get a good idea of the diversity of insects in Germany,” says Hans de Kroon. He’s an ecologist at Radboud University in the Netherlands. He helped with the study.

Starting in 1989, researchers used special traps to collect insects. These traps have a large net shaped like a tent. It funnels insects into bottles, where scientists can collect them. The trapped bugs show researchers what type of insects are in an area. They can use the small sample to calculate how many insects there are overall.

Volunteers set up and checked the traps every year for the next two decades. They recorded the position of the traps extremely carefully. They put the traps back in the exact same spot each year.

“We already knew that some insects were in trouble,” de Kroon says. People had been tracking bees and monarch butterflies for years, and they expected to find a decrease in other species too. But they did not expect the decline to be so dramatic. And the situation isn’t unique to Germany: Another study found that 41 percent of insect species around the world are dying off rapidly.

Flying insects are a vital part of the food chain. They pollinate fruits and vegetables and are important food sources for birds and mammals. Declining insect populations could eventually lead to a loss of bird life and plant variety.

But there’s room for hope, according to de Kroon. “Insects, as almost no other group, have enormous potential for recovery,” he says. “Sometimes you see many generations in a year because they can lay hundreds of eggs. If we manage to improve the conditions, they can quickly recover.”

“We already knew that some insects were in trouble,” says de Kroon. Populations of bees and monarch butterflies had been dropping for years. The researchers expected to find a decline in other species also. But they didn’t expect it to be so bad. And the situation isn’t unique to Germany. Another study found that 41 percent of insect species around the world are dying off rapidly.

Flying insects are an important part of the food chain. They pollinate many fruits and vegetables. And many birds and mammals eat the bugs. Declining insect populations could eventually lead other animals and plants to die.

But there’s hope, says de Kroon. Insects can lay hundreds of eggs at a time, which could help them bounce back eventually. “If we manage to improve the conditions, they can quickly recover,” he says.