Leaf Curl

My young apple and plum trees have leaf curl together with the nasty little bugs that go with it, so I was wondering if there is an effective treatment you have used with positive results, many thanks for your replies, much appreciated

 

Can you see what the insects are? Aphids?

 

The big problem is general spraying does not work as they live under the leaves. I just dug up my young pear tree for that very reason as I had leaf curl every year since I bought it. Every leaf was infested. Maybe some hard pruning might help. Plum trees now and apple trees in the dormant season. Then dispose of the cuttings.

 

Only a systemic spray is going to kill them in my opinion.

 

I've had some success with a combination of:
-a sticky barrier on the trunk to prevent the ants from farming the aphids
-painstakingly uncurling the leaves and using a handheld pumpsprayer filled with water to jet the aphids off

...if it is aphids?