Watch a caterpillar turn into a butterfly, in 3D

What happens inside a caterpillar's cocoon? Scientists got to watch the whole process with the help of X-ray 3D scanning technology. In the video above, you can watch a caterpillar turn into a butterfly. Over the course of 16 days its breathing tubes (shown in blue) and its digestive system (shown in red) change shape and position within the body, while other structures grow from scratch.

Ed Yong has a great story to go with this, too. All about why it's important to actually watch the process happening in a single caterpillar, instead of just relying on the data scientists have collected from years of dissecting different caterpillars at different stages in the transformation.


  1. David Brin’s excellent sci-fi novel Kiln People employed the colorful metaphor that the caterpillar, rather than metamorphosing into a butterfly, is more accurately devoured from within by the new organism.  But I guess that was more artistic license than it was actual science.

  2. well, I wouldn’t use the term ‘from scratch’ as a scientist, it’s inefficient.
    from genetic potential maybe? or from the ether?

  3. Fantastic & enlightening (I thought I already knew all about it.  I was wrong!)…  thanks Maggie!

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