What is eating the leaves on my pear tree?

Hi. I know the year before last aphids completely destroyed my apple tree. I have seen a few greenflies but to me it doesn't look the same as that. I may be wrong. Something seems to be eating the leaves, and I've lost a few flower heads because of it. What is it? Not all branches are affected. But I don't know what to do. With the aphid problem I just hose piped them to death. And just about saved this tree. The other died, as stated. Please help. How do I stop this pear going the same way as the apple tree. Thanks in advance.