Insects migrate in wind highways

Migrating insects use highways in the sky to speed their journey.

Researchers say moths and butterflies use sophisticated methods to find winds that will take them in certain directions for thousands of kilometres.

The little creatures travel on winds of up to 100km (60 miles) per hour.

They use internal compasses to find these fast moving winds to carry them to their journey's end.

Sky highway

It may seem a little difficult, in the depths of winter, to imagine sitting outside on a balmy summer's evening gazing up at the velvety night.

But, if you can, cast your mind's eye back because above you was a windy highway used by thousands of these delicate migrating creatures.

And the same journeys are sometimes carried on over several generations of insect.

The scientists say that each insect uses the same complex methods to whisk them to their wintering water-holes in the Mediterranean and back to more northerly climes in the summer.

"We were surprised by the scale of the movements, although we wouldn't have started the research without some idea of what was happening," says Dr Jason Chapman of the Rothamsted Research Institute in Hertfordshire, UK, who is the lead author of the report.

"What is also surprising is that very few of the insects end up going the wrong way".

But most moths and butterflies look like they can hardly make it across the garden. So how to they avoid getting ripped to shreds in these fast moving winds?

"When you are flying within the windstream you don't feel it" says Dr Chapman. "Having said that, we think the way they choose the winds that are fastest is through some sort of turbulence mechanism.

"As the data has built up over the years we have been amazed by the subtlety and sophistication of the system."

It is still not known exactly how this mechanism works - that will be for further study.

The group that published the research is one of only three is the world using special radar that can detect insect movement up to a kilometre in the air.

And, while the research is fascinating in itself, it has useful applications. "One of the people working on this research has also been working on data about the midges that carry bluetongue", says Dr Chapman.

"Hopefully other scientists' prediction models of the future, for some of the moths that could become invasive pests in this country, will incorporate our research".