Vine Weevil Infestation
There are very high numbers of Vine Weevils in many areas this year, so it could well be the problem. The edges of leaves will often suffer damage that looks like a half moon cut. Adults sometimes can be seen on walls or in bushes but they are often nocturnal. There is not much you can do about the adults apart from squash where you see them! However the larvae part of the life cycle can be treated with nematodes. Try applying Vine Weevil Killer nematodes to pot and containers and to the base of plants in open flower beds. You should apply the nematodes before October and you may need to repeat in the spring as it is difficult to kill all the Vine Weevil larvae with one application. I hope this helps.