I don't think they will. I have Googled hawk moths and they feed on a variety of leaves including fuschia, privet and cherry. I don't think apples themselves are on the menu!

Thank you Cammomile, it just seems odd that they have made a home in the apple tree and there a few webby things there with caterpillars inside.

Hi there,
Actually Apple (as well as other Malus species) is very much one of the regular foodplants of the Eyed Hawk-Moth.

If it were me I'd be absolutely thrilled - these are some of the most spectacular insects in the country. The caterpillars won't have any interest in the apples themselves, they simply eat the leaves, and are not normally found together in large numbers, so they won't effect your fruit crop at all.

I'd happily give them a home in my garden

Me too Moon_grower!

Lovely and thank you, I have loads of them and they are in little silken webs. I did move one lot, before I knew what they were, and put them on a seperate apple twig. It was amazing how quickly they formad a coccoon around the leaves and you can watch them all moving about. The female moth is in the tree and the male flew away. They are welcome to the leaves as long as tjhe apples are fine and if they all survive, I should have a good display.