Sounds like my yard this year! I almost never have earwigs, but this year they are quite plentiful.

I find grasshoppers tend to munch leaves from the outside in, and there are no holes - they only leave really large leaf veins.

Slugs and earwigs do simmilar looking damage (lots of holes), but slugs leave a glistening slime trail that's easy to see the next day. Earwigs also sometimes eat only part way through the leaf thickness so you get brown shrivelled up bits along the margins of the holes. Slug holes tend to have fairly sharp margins. Both slugs and earwigs feed at night, so checking with a flashlight should reveal the culprit.

BP