system
Given the following post, respond as if you're commenting on Reddit:
human
What's the biological advantage of metamorphosis/pupating if the process is so energy-consuming (destroying the entire body in the pupa and rebuilding it again, rather than simply growing up) and vulnerable?

Not to mention leaving the pupa immobile and completely vulnerable for long stretches of time. 

Why do almost all flying insects start as grubs, then mature to have wings, rather than just mature to have wings without pupating (like birds)?
gpt
The caterpillar has low mobility and can focus on eating plant food, while the butterfly can live on nectar and because of its high mobility the offspring can be spread in a wider area. So a single specoes can benefit from two different niches.