Divide mesh by colour

Hi all, 

I have a mesh coloured in red (sun) and blue (shadow) from ladybug. I need to divide the mesh by colour, having one mesh for each colour area.

I have all the vertices in a list with a 1 for red and a 0 for blue, but i don´t know how to get all the index that have 1 as item, and then use them to get the vertices that have these index, and with these vertices get the mesh that correspond to the red area...

Or maybe I can do something deconstructing the mesh and using the colour information, but I don´t know how

Please I need help 

Eduardo.