Bees don't eat leaves :-) Leafcutter bees do take portions of various leaves and use them to make nests (perfectly harmless to the plants) but otherwise, bees feed on nectar and pollen and with some wasps and hornets, also on fruit, carrion and other insects. But no plant parts :-)

If you can manage to photo these critters and their damage, maybe we can clarify for you what's going on. But I doubt your trees have anything to worry about.