In the spring, the female monarchs leave Mexico and fly as far north as the American state of Kansas.

VOA: special.2010.04.27

Professor Taylor is urging people in the southern United States to help the monarchs by planting milkweed.

VOA: special.2010.04.27

Professor Reppert says scientists thought they understood the control system in the monarchs until they took a closer look at the insects' antenna.

VOA: special.2010.04.27

He says fewer monarchs are returning this year than any other year he has witnessed.

VOA: special.2010.04.27

Many players slept on the bus. Jackie Robinson played for the Kansas City Monarchs.

VOA: special.2009.04.05

The researchers then purposely interfere with the monarchs and follow their movement again.

VOA: special.2010.04.27