Mario & Luigi: Bowser's Inside Story/Flame Pipe

Scutlet
Keep scaling the ledges and use Mini Mario to enter the alcove and open the next room. There is a huge Scutlet bug blocking Bowser's pipe. Scutlet eats Starlow and uses her and it's tongue to attack. Use Fire Flower and Green Shell to max out your damage. Jump on it's tongue and hammer Starlow when defending. When it is beaten, Bowser can use fire breath.

Now head back to Plack Beach!