I thought originally that the holes in our rhodie leaves were caused by slugs, although I didn't see any slug trails. The holes are large and often quite circular. Sometimes a leaf is eaten to the point that only the main vein is left. Someone mentioned the root weevil to me, but I haven't seen any of the adult critters on the plants. And the damage looks considerably different from what I have seen in the pictures. I have found several pale green caterpillars, something over an inch long, and maybe 3/16" in diameter. Could they be the culprits? And what is the solution to getting rid of them?
Finding catapilers is certainly suspect especially as large holes are present (and assuming fresh young tasty leaves). Various bees can also do that, to collect paper for nests, however, since you finding catipilers is what I would go with. Treatment depends on the degree of the problem -- you can simply pick them off if a few or if troublesome you may want to consider insecticide.
BTW, I think one reason post like this are left unanswered is because of insufficient or too general info. Pictures are worth more then words -- that always help, but when it comes to holes, well, that could be anything.