From Caterpillar to Chrysalis—and What Happens in There

Even though it's still snowing in some areas of the United States, spring has technically arrived. To celebrate, watch the mesmerizing and soothing video below of a monarch caterpillar performing one of nature's greatest magic tricks: Transforming into a chrysalis, after which it will emerge as a beautiful butterfly (Danaus plexippus).

For a long time, what happened in the chrysalis was a mystery. It was sort of like nature's magic trick: A caterpillar disappears into a chrysalis and emerges a butterfly. But last year, research conducted using state-of-the-art technology gave the world a peek inside the chrysalis during metamorphosis.

To conduct their research, scientists used a micro-CT scanner—a version of the machine that doctors use to find internal injuries in people—and nine pupae of one of the world's most widespread butterflies, Vanessa cardui. They hung the chrysalides inside a straw and spun them as they took almost 2000 x-rays, which they used to create highly detailed 3D portraits of the transforming insects at various stages of the transformation. Below, you can see an image of an adult specimen on the sixteenth day of development. 

Tristan Lowe

The scans revealed that most of the tracheal system of the butterfly forms in the first day of pupation; the midgut is formed and in position by day 7 (though it will continue to develop through the transformation). The scientists, who published their study in the Journal of the Royal Society, believe that this method of scanning could be used to learn more about the development of a wide variety of other insects, too.