I just want to clarify which pest you are dealing with. Apple maggot can be a problem in fruit, but codling moth is another fruit-burrowing larva and at least in my experience is far more common. I've posted links to the discussion in the Pacific Northwest Insect Management Handbook of each of these pests. Perhaps if you look these over, it may be possible to distinguish which pest you are dealing with. If not and if you have any infested apples you can bring to the Marion County office, we can help you make that determination.
http://pnwhandbooks.org/insect/tree-fruit/apple/apple-apple-maggot

http://pnwhandbooks.org/insect/tree-fruit/apple/apple-codling-moth