aphids

i have noticed several out breaks of aphids in my green house can anyone tell me a good way to get rid these little pests. I preffer to not use chemicals and would rather use something organic any sugestions plz thanks.

 

I've suffered a few whitefly in my g/house and have controlled them with a daily misting and raising the humidity.

 

I found a few in my greenhouse and decided to try 'putting up' a few ladybirds (rent free of course ) that I caught from the garden and its definitely worked, there are very few left..