The transformation from caterpillar to butterfly is one of the most exquisite in the natural world. Within the chrysalis, an inching, cylindrical eating machine remakes itself into a beautiful flying creature that drinks through a straw.

This strategy—known as holometaboly, or complete metamorphosis—partitions youngsters and adults into completely different worlds, so that neither competes with the other. It’s such a successful way of life that it’s used by the majority of insects (and therefore, the majority of all animals). Butterflies, ants, beetles and flies all radically remodel their bodies within a pupa as they develop from larvae to adults.

But what goes on inside a pupa? We know that a larva releases enzymes that break down many of its tissues into