Every autumn, a quiet mountain pass in the Swiss Alps turns into an insect superhighway. For a couple of months, the air thickens as millions of migrating flies, moths and butterflies make their way through a narrow
opening in the mountains. For Myles Menz, it’s a front-row
seat to one of the greatest movements in the animal kingdom.
Menz, an ecologist at the University of Bern in Switzerland,
leads an international team of scientists who descend on the
pass for a few months each year. By day, they switch on radar
instruments and raise webbed nets to track and capture some
of the insects buzzing south. At sunset, they break out drinks
and snacks and wait for nocturnal life to arrive. That’s when
they lure enormous furry moths from the sky into sampling
nets, snagging them like salmon from a stream. “I love it up
there,” Menz says.
He loves the scenery and the science. This pass, known as the
Col de Bretolet, is an iconic field site among European ecologists. For decades, ornithologists have tracked birds migrating
through. Menz is doing the same kind of tracking, but this time,
he’s after the insects on which the birds feast.
Migrating insects, like those that zip through the Swiss mountain pass, provide crucial ecosystem services. They pollinate
crops and wild plants and gobble agricultural pests.
“Trillions of insects around the world migrate every year,
and we’re just beginning to understand their connections to
ecosystems and human life,” says Dara Satterfield, an ecologist
By Alexandra Witze
Researchers are asking big questions
about animal movements by tracking
tiny insects in flight
This hawk moth
(Hyles gallii) is one of
millions of insects
that migrate through
a Swiss Alpine pass