My uncle was a biology professor at University of Michigan, and he used to raise these caterpillars as experimental subjects to study insect metamorphosis (and, by extension, cell differentiation in other animals). He used them because (a) they were easy to raise; (b) they were native to the state, so if they got away from the netted trees he was raising them on they wouldn’t turn into an invasive species problem; and (c) they were so huge that they were way easier to examine and dissect than a more normal-size caterpillar would be.

The bit about the size sounds a lot like something Victor Frankenstein said:

“As the minuteness of the parts
formed a great hindrance to my speed, I resolved, contrary to my first
intention, to make the being of a gigantic stature, that is to say,
about eight feet in height, and proportionably large.”

They aren’t quite big enough to take on a bat in hand-to-hand combat, though. There’s a spot on one of our campus buildings where bats like to hang out, and last year I found a complete set of Cecropia wings, sans body, on the ground right under the bats. And, a few days later, a set of Luna moth wings. Some bats must have eaten very well those nights.