Steve, congrats on your observation skills. I never noticed what you observed by yourself until Lee Reich pointed it out to me several years ago. Plum curculio larvae usually don't survive in apples- they are crushed by the rapidly expanding cells. Unfortunately the damage is usually a lot more than cosmetic as fruit is terribly disfigured with numerous hard spots and becomes virtually useless especially for storage and even eating off the tree. Michael Phillips describes their life-cycle wonderfully well in "The Apple Grower".