The right color blocks can help in this Level, but here are some more important tips:
Watch where the butterflies are and concentrate on the easier one to fill, don't waste time on a butterfly that will be destroyed by the line blaster before you can fill it!
Use paint to join large groups of the correct color
If a balloon is the color you want to fill a butterfly, DO NOT use it in the level until you have the 16 blocks needed.
Once you pop a balloon and remove that color it will not come back until the board has been cleared of all other colors.
A good way to do this is to remove large groups of blocks in other colors and let more of the one you want fall.
Leave the balloon for the line blaster - hopefully by the time it gets there you'll have 16 of that color.
The second play through of the Level shows this way of playing
If you do not have any blocks the correct color for the butterflies, then use the balloons to get down to one color.
Once that color is removed the board will be multicolored again.