This should be pretty basic thing to know, but I still don’t really grasp PC damage in apples.
To start: I’m growing fruit for me, doesn’t have to be perfect. Also, I prefer not to spray. Last year I did a spectracide spray after petal drop and still had PC damage on the large majority of apples. They didn’t really bother the pears. There are multiple large, old apple and pear trees in the neighborhood that are pretty much ignored and left to the deer/squirrels which I’m sure harbor lots of fun pests.
If I do not spray for Plum Curculio and later on bag my apples, what will happen to apples (and pears) that have eggs laid in them? Most university articles are non-tolerant of any damage and indicate that some portion of the damaged fruit will drop.