1. First activate the star switch so that the passage in the lower left corner gets blocked. Then push down the apple.
2. Wait until the blue muncher has passed by the closed gate. Then activate the star switch again so that the red muncher leaves the room first.
3. Wait until the munchers have opened the way to the two color switches. Change your color and remove the purple and green blocks. Now you only have to wait until the red muncher destroys the last red block.