Question

Why do caterpillars move when you scream?

Answer 1

because it is afride

or caterpillar breath through skinits skin shatters when we screen

Answer 2

It turns out caterpillars writhe their bodies and shake their heads when they hear loud sounds because they are warding off potential attacks from parasite flies. The sound of John's scream is at a similar frequency to that of the parasite flies, triggering the reaction in the caterpillars