Cherry tree bugs

Looks like I had a sever insect/bug infestation on my Cherry tree this year, the season look good with lots of blossom but then I later noticed leaves going black. I had to resort to some severe pruning in the hope that next year may be more fruitful. Some pictures of the leaves and also of the bug are attached, one picture shows a sticky gooey mess. can anyone help me with a remedy. After pruning all was burned and the tree was give a good spray with Provado.