Hi i have some fruit trees and the top leaves have green fly and black fly on them they are also teaming with ants who appear to be dealing with this problem by eating the flys would this be ok to let this continue as i'm not a great fan of chemical etc the greener the better for me any advice will be gratefully received thanks
Firstly, the ants are not eating the aphids. They stimulate the aphids, who in turn secrete a honeydew substance which the ants farm off of them.
Washing-up liquid diluted with water, is a very good non-chemical solution to the green/black fly problem. Spray this on all the leaves. I was going to suggest ant powder to stop the run, but if you don't want to use it, I can understand.