This guide shall help you to paint any wings - not only for Scourges, but for any Tyranids or heavily mutated Chaos Space Marines. Special thanks for the guide to David Soper
It's necessary to use a white primer. Then apply Rakarth Flesh. Wash it with mixture of Seraphim Sepia + Reikland Fleshshade 1 to 1, and don't forget to use some lahmian medium.
The other surface is done the same way, but with more intense colours. Improvise!
Beautiful models need beautiful table! And it can be bought here