Icing question

DD turns 2 on Sunday and I'm making her a very hungry caterpillar cake. How do I get the icing on the cake to have a two different colour effect?

It will be buttercream frosting, and the caterpillar's colours are a light green against a dark green and I'd love to capture that. Do I make the separate icings and put them together, without mixing them, in the piping bag?

you could possibly not mix the colour threw the icing properly, so it comes out kind of darker in bits yet lighter elsewere? or do dark then go over with a thin layer of lighter in certain spots?:dunno:

I think it would be better if you iced the cake in one green (the lightest shade), then using a brush, paint on patches of darker colouring. You may want to practice first.

I did a hungry caterpillar for DD's first birthday and what I did was ice it in one shade of green and then dyed coconut in different shades to sprinkle over.

Thanks for all the tips girls, will let you know what I end up doing and how I go :)

Id have a practice of putting the two shades together in the piping bag...if it turned out how I imagine it to it would look pretty good