I'm writing a species of dragon-sized butterflies¹ as flying mounts into a low-magic fantasy setting², and would like to know if these creatures have to be imbued with magic, or if they could just be mundane through some contrivances. What stands in the way of having an insect of this size, and how can we get around it?
I recognize that this question deals with the square/cube law, and the implications it has on creatures of this size - I was just wondering how it differs in the context of insects (Lepidoptera specifically).
¹ I'm looking for sizes ranging from 10-22 feet in height, and 40-150 feet in wingspan, varying by species. I don't mean to have Kaiju-sized butterflies.
² Assume conditions analogous to middle-age Earth (with the addition of magic)