I would have thought moths as well. If it is codling moths then it is too late to do anything this year. Some pheramone sprays work for moths as does putting cardboard along branches - you do that, attract the moth caterpillars and kills them.

Don't forget that quite a few apple types only fruit every second year, so it may not be as sinister as it sounds. Kildermorie is spot on about it's being too late to treat for codling moths. Codling moths, I think, eat the fruit itself, rather than the leaves. I think this might be another kind of moth, and a healthy dose of systemic pesticide would see off any leaf-nibblers. If you do spray, please do it at dusk, when it isn't likely to affect any pollinators such as bees. Inspect the leaves as often as you are able (especially the undersides) and dispatch any caterpillars you find to stop them spreading.

Apples and pears can be very frustrating to grow in the garden as they have the on off fruiting, as mentioned above, and lots of critters want to get at all parts of the trees. Grease banding in early October, messy job. Spraying is up to you on edible crops. I see snails well up my apple trees; I expect they are dining out. Watch out for tent caterpillars from now on and remove when seen and squash!Thin out your crops too, if reachable. This may or may not help with on off fruiting, but worth a try, if you can be bothered to do it. I have ten trees and some are in fruit and others.....resting.

Oh is that what you call them? Tent caterpillars! Well, I never! I take your point about spraying edible crops, but at this stage the fruit is still so small, I think it is a fairly valid option.
It's strange, isn't it? I have never seen snails up any of the fruit trees, although we have a massive population of them in the orchard. That's where the neighbours' ducks come in and have a picnic, and are, for once, encouraged.

I have a nightmare vision of racehorse-sized snails rampaging through pear trees, Gattina!

Pretty close, M!