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Monarch butterflies may have magnetic compass

Wednesday - 6/25/2014, 5:04pm  ET

FILE - In this July 22, 2012 file photo, a Monarch butterfly eats nectar from a swamp milkweed on the shore of Rock Lake in Pequot Lakes, Minn. A new study published in the journal Nature Communications suggests that monarch butterflies use an internal magnetic compass to help navigate on their annual migrations from North America to central Mexico. (AP Photo/Ann Heisenfelt, File)

MALCOLM RITTER
AP Science Writer

NEW YORK (AP) -- A new study suggests that monarch butterflies use an internal magnetic compass to help navigate on their annual migrations from North America to central Mexico.

Scientists already knew they navigate by the sun. But the insects do just fine on very cloudy days, leading to suspicions they also use a magnetic compass, like migratory birds and sea turtles. Previous studies haven't made a clear case for that, according to authors of the new study, from the University of Massachusetts Medical School in Worcester and the Worcester Polytechnic Institute.

They tethered monarchs in a chamber without any outdoor light and showed that their flight patterns responded to changes in the magnetic field. Further work suggested the compass is in the antennae.

Millions of the black-and-orange butterflies spend the winter in Mexico.

The new work was released Tuesday by the journal Nature Communications.

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Online:

Nature Communications: http://www.nature.com/ncomms


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