Help I'm losing my basil

I had the same problem last year. Little tiny holes appearing in the leaves of my basil plants. I have inspected the plant and don't see any critters. I thought itmight be slugs so I got soemthing to put around the plants but that evidently isn't the problem because I see more holes. Last year I had to replant 4 times and finally gave up. Does anyone have any suggestions?

BFLY :(

Have you tried looking at night with a flashlight? Maybe a nighttime bug or slugs that appear at night.

Newt