Trillions of bugs are buzzing over our heads, study finds

Ever wonder how many bugs are buzzing over your head at any given time? Well, British scientists did, and the results from a decade-long study found literally trillions of insects zoom over southern England each year.

It's the first study to pinpoint the precise number of bugs that buzz over a region.

"Insect migration is hugely important, as many of the species are either harmful pests or beneficial (predators or pollinators), so we want to know how many are moving, and where they are coming from and going to," said one of the study's authors, ecologist Jason Chapman of the University of Exeter.

In all, about 3.5 trillion insects migrate both north and south over southern England every year from May to September, the study said.

Researchers from the University of Exeter and Rothamsted Research used an upward-pointing radar beam, along with nets hung from a blimp, to count the number of bugs flying around.  They looked for bugs at 500 to 4,000 feet above the Earth's surface.

Weather radar, which is typically used to pick up precipitation such as raindrops and snowflakes, often accidentally captures swarms of insects instead. In this instance, the scientists used special radar to actually look for the insects.

This annual movement of these 3,200 tons of bugs is more than seven times the mass of the 30 million songbirds that depart the U.K. for Africa each autumn. By weight, that's also equal to about 800 elephants. In a seasonally appropriate comparison, scientists added it's also the same as 20,000 flying reindeer.

The numbers of bugs buzzing around are likely higher in other, warmer parts of the world, the scientists said.

If the numbers found over the southern U.K. are extrapolated to how many bugs fly over all continents, "high-altitude insect migration represents the most important annual animal movement in ecosystems on land," Chapman said.

​Scientists found most bugs moved around during the daytime and migration intensity was greatest on warm days with light winds. The insects also seemed able to select tailwinds to migrate where they wanted to go.

Seasonal migration was thought to be rare among insects. The discovery that so many species were using winds to migrate across the country "was a big surprise to us," Chapman said.

The research was published Thursday in the peer-reviewed journal Science.