Suggest that you do a SEARCH within ths forum for the key words 'eating Basil'. It will bring up a LOT of recent posts about the same exact issue. Its much better to do a search, as opposed to reposting the same question which seems to get repeated many times in a month.

I am having the same problem with my basil, here in southern NH, and I discovered the culprit last night! I went out to the garden with my flashlight to pick some basil leaves and found tons of coppery-brown beetles munching on them. I have 10 basil plants and found at least a few on each plant. I knocked them off, but was afraid that the plants would all be gone by morning! I did check today, and half of my plants are completely chewed up. I have no idea what types of beetles these are (def. not Japanese beetles), or if there are any organic control methods for this. If anyone else has thoughts on this, that would be great!

I personally am not very good at identifying without a picture (sometimes WITH a pic) the black spots could be poops. How big are the holes... and is it indoors or out?

You need to check very carefully for caterpillars, perhaps after sundown with a flashlight. That's caterpillar frass. Those little specks aren't black but very dark green bundles of compressed basil waste.