BOB HIRSHON (host):
How Monarchs find their way. I’m Bob Hirshon and this is Science Update.
Every fall, millions of Monarch butterflies migrate from North America to the high plateaus of Central Mexico. They navigate using a structure in the brain called a sun compass. But since the sun appears to move across the horizon over the course of the day, they need a way to compensate for this. According to neurobiologist Steven Reppert of the University of Massachusetts Medical School, that’s where their antennae come in. He and his colleagues found this out when they removed the antennae of some butterflies and put them in a flight simulator.
STEVEN REPPERT (UMass Medical School):
What we found is that the butterflies that didn’t have their antenna were completely disoriented, whereas butterflies without their antenna manipulated were flying normally in the southwesterly direction, which is exactly what you would expect when headed toward Mexico.
I’m Bob Hirshon, for AAAS, the science society.