idk if these will be too similar to other names submitted, but here goes something...
Stage 1: Curva (Cuprum + Larva)
"Cu" derives from Cuprum, which is Latin for Bronze, & "rva" derives from Larva, representing it being the first of the three stages of Larva > Pupa > Moth. Pretty simple, mind.
Stage 2: Aggoon (Aggro + Cocoon)
"Agg" derives from aggro, which is short-hand for aggression, & "oon" derives from Cocoon, representing it being the second of the three stages of Larva > Pupa > Moth. Though Cocoon iirc, is an alternative name for Pupa.
Finally, there is Aurumoth, but yeah. Also, this follows the periodic table characters theme for a progression of Curva > Aggoon > Aurumoth.