If I recall correctly, the proc chance on wrath for starfire is so low, its not worth planning for. I'd stick with

Code:
/castsequence Moonfire, Insect Swarm,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
/cast Wrath
With wrath having such a short cast time, the sequence lag for a /castsequence involving wrath will really drag down your dps.