This is what I call “my big Larch”.A good friend of mine called over last week,Bonsai eejit, he had noticed the pest and that the wire was biting in a little.
So today I treated with a suitable pest controler, removed these cones and,,,,,,,
Removed the Jin that was on the very top of the tree.I will spend another afternoon this week and take off the wire that is just starting to get to tight.
Bonsai Baker 
we have seen that particular aphid on a couple of larch this year , it seems to be worse on European , you can blast quite a lot of them off with the hose set to a fine but powerful jet
Peter how did you treat this aphid?