Butterflies use Earth's magnetic poles to migrate south

Rachel Zabel's fourth-grade class at Hawthorn Elementary School North in Vernon Hills asked: "How do butterflies use their antennae to migrate?"

Butterflies are insects - they have six legs, their skeletons are on the outside of their bodies and they mature in a life cycle called metamorphosis. Starting as a tiny egg, butterflies grow into a caterpillarlike larva; they then change into a pupa and finally emerge as an adult.

Body parts on these delicate insects include a head, thorax and abdomen. The antennae are attached to the head and are covered in chemoreceptors that react to certain chemicals in their environment, giving butterflies a sense similar to smell.

"The receptors are used for close-range sensing," said Doug Taron, curator of biology at the Peggy Notebaert Nature Museum in Chicago.

Females use antennae to sniff out the best place to lay eggs. An organ at the base of the antennae helps butterflies to hold their balance when flying or perching on a leaf or flower.

Monarchs are the butterflies that migrate. Scientists believe that sun and the magnetic poles help direct them to warm destinations in the winter and back north again in the summer.

"We know that they use the sun's angle in the sky to guide them south," Taron said. "There's some evidence that they can detect the Earth's magnetic field."

These direction detection tools are not found in antennae.

Immerse yourself in butterflies year-round at the Nature Museum's Judy Istock Butterfly Haven, an exhibit in a greenhouse setting containing more than 75 live species of butterflies and even few small birds.

"It's the only place in Chicago where you see butterflies at this time of year," Taron said.

The greenhouse is filled with tropical trees, flowers and pools where butterflies flutter to sip water or perch and rest. Every day museum staff release newly emerged butterflies at the exhibit.

For information about the butterfly haven or about free field trips for Illinois students visit naturemuseum.org.