That could be earwig damage, or many other things as well. Earwigs, as a rule, are digesters of decaying organic matter as well as many insects, they are benficial because they are predators. Since the same conditions that earwigs like, and need, are the same as slugs like and need many times because people see earwigs quicker then they do slugs the earwigs get blamed for the damage slugs do.
Try spraying the plants with cold caffienated coffee.

Here is a link that might be useful: About Earwigs

Sharp notches as shown in your photo can also be weevil. You're going to need to go out with a flashlight after dark and look, see what pest you are dealing with.

That looks exactly like damage from the Black Vine Weevil, a pest of many different kinds of plants. No picky feeder, this one; you'll find it on almost anything.

Ditto that thought.

Further, earwigs are messier when they eat. Holes usually have ragged edges.

Third the weevil.

Dan

I would go out with a flashlight.
I suspect various night feeding caterpillars. This does look a lot like Weevil damage, but the notches are not distinctive enough to lead me to this conclusion. You can find weevils hiding in shady areas under duff and rocks etc. when it is hot and sunny. Look under the plants then. You may also have Weevils but I suspect caterpillars are doing most of this damage.

Betcha a dollar that these are black vine weevils, lol. Take a look at some examples of the damage they can cause on a variety of plant species.

By the time a hoard of weevils are finished with a leaf, there might not be much left.

Here is a link that might be useful: Click here

Rhizo you are on for the buck. I am sure there are Weevils also, but most of the chewing I would put on the night caterpillars. I have seen weevils eat just about all of a rhododendron leaf but the margins are still distinctively notched.
Btw the best control for BVW are dead fall traps. Containers buried up to the rim with a shady board over them and a ring of grease about 1" below the rim. Up till now no chemical has been effective against this pest. I am told by Stan Swyer UNH that the new acelepryn will kill them but have not tried it yet, and at close to $2000/half gallon am unlikely to for a while"

Oh, my goodness! I think it might just be black vine weevils! I looked up photos after I read all of your replies and the photos of damaged leaves look so much like my azalea leaves, especially. I uploaded one of them.
I have been out several nights with a flashlight prior to posting my question, trying to catch SOMETHING in the act, but I haven't seen these beetles. In fact, all I have seen are a couple of earwigs, leading me to surmise earlier they must be the culprit.

Beer traps haven't caught much this year, and the veggie oil traps have so far only caught many amber-colored beetles that I always believed to be harmless....hmmm. I have not covered the can with a board, though, so I will start doing that.

BUT I remember a few weeks ago, when this was all starting, my husband reporting to me one morning that as he was leaving the house he noticed a hundred or more beetles (not amber colored) in a clump near where we have a lot of plants. I wonder if he had come upon a fresh spring litter of BVWs?? I'll ask him tonight!

IpmMan, I would love to win you $1 but it will take more night-spying on my part to find catepillars...or anything, for that matter. Methinks these buggers have a sophisticated cloaking device.

Here is a link that might be useful: {{gwi:1182236}}

Yep, the damage you've shown us is clearly that of the weevil. That's not to say, however, that somewhere along the line you won't also be visited by other chewing insects. Keep your eyes peeled for the 'friendlies', too.

Try the dead fall traps. See how many you catch.
Though I have seen severe Weevil Damage in Nurseries. I seldom see heavy damage in landscapes unless someone has killed off predators using Bifenthrin or other predator killing chemicals. The diversity in landscapes usually keeps the ground beetle and other predator populations high enough to keep Weevils under control. As a side note some of the mosquito killing companies use Bifenthrin so if you are having someone treat for them make sure you know what they are using.