Somewhere along the way I also learned that the Monarchs migrate to Mexico each year from the mid and northern United States. That, in itself, is an amazing feat. However, when you consider the life cycle of the Monarch, it becomes downright Magical.
Monarchs generally live about six to eight weeks. The egg stage is about four days, the caterpillar stage is about 14 days, the chrysalis stage is about ten days, and the butterfly stage is about 2-6 weeks.
There are four generations in a year. The first generation returns to the north, and does the eggs/caterpillar/Chrysalis/butterfly thing. Generation two and generation three follow, about every two months. Generation four hatches in September/October, and it is THIS batch that migrates.
Now I wanna know: how DO they know?