Very nice! I like the subject.

I find the word "powdered" out of place because of the science. While still inside the cocoon, the wings are wrapped around the pupa and are very moist and supple (they actually are formed under the caterpillar's skin first). Dry and powdered is after they emerge and let their wings dry and pump blood into them...

Butterflies and moths go through the same kind of metamorphosis, but butterflies don't form a cocoon. Only moths do (some don't, there are some that form underground instead). All butterflies form a chrysalis, not a cocoon. So most moths do their pupa stage in a cocoon, all butterflies do theirs in a chrysalis.

=Bob=