Moth that can travel at 55mph

Moths that fly high above our heads throughout the night are not at the mercy of the wind but use a sophisticated internal compass which can help them travel up to 400 miles in a single flight, according to a study.

	Silver Y moths, by selecting the fastest moving layers of atmosphere, can cruise at speeds of up to 55 mph

While it is not clear how the creatures - in this case, the Silver Y moth - actually navigate between sunset and sunrise, researchers from the UK and Germany have found that the insects can judge the best conditions for flight based on direction and windspeed, selecting the fastest moving layers of atmosphere so, with their own speed of 10mph, can cruise at speeds of up to 55 mph.

Dr Jason Chapman, of Rothamsted Research in Harpenden, Hertfordshire, says: "There has been speculation for many years about whether insects that rely on wind for migration can have control over the direction in which they migrate.

"If they didn't have any control then, in many years, the autumn population would get blown in unsuitable directions and die - the so called Pied Piper effect," he says. "Our studies demonstrate that the moths can influence their direction and speed of movement in a number of ways."

The team found that moths only migrate on nights when wind direction is favourable. The most unexpected finding was that moths could compensate when wind direction was off target, suggesting they have a compass.

Dr Chapman a says: "The moths must have a compass mechanism, similar to that of migratory birds.

The cues used by the insects to set the compass are not known. Day flying insects use the sun or landmarks to navigate. Moths do not have good enough eyesight to use stars, he explains, and the moon's movements are too unpredictable, leaving a magnetic sense as the likeliest one they rely on.

The research was carried out using radar and showed that in August an estimated 200 million Silver Y moths migrated southwards over the UK to breeding grounds in the Mediterranean. The data, from 2003, has only just been processed and is published in Current Biology.

He said there are important implications of the work in helping to warn farmers if pests are about to attack crops. "Considering the high pest status of many insect migrants, and the effects of global warming on the frequency of insect migration, the long range movements of such pests will have increasing impacts on global agriculture."

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