It's even more mysterious once you realize that metamorphosis is a later evolutionary development. Early insects hatched out as miniature adults and molted as t

It's even more mysterious once you realize that metamorphosis is a later evolutionary development. Early insects hatched out as miniature adults and molted as they grew, as do arachnids and crustaceans today. So to evolve a larval stage they had to evolve a whole separate new organism from the ancestral one, so to speak.