Japanese beetle traps will help. The traps contain a “lure” to attract beetles so the trick is to put them AWAY from what they are eating…You’ll still have to pick some off but not as many.

Lydia–basil is delicious and slugs, Japanese beetles and aphids think so, too. It’s most likely slugs–and you often don’t “see” them because they are active at night. If the leaves look somewhat “lacy” it might be Japanese beetles, because they don’t eat the veins of the leaves. I doubt it’s Japanese beetles because you’d most likely see them as they’re out during the day. Because slugs seem to be the number one fans of basil, that may be it. One thing you can do is get a product called diatomaceous earth and sprinkle it over the soil under the plant. Slugs won’t crawl over it. The other thing to do is, if the basil is in pots, get them up off the deck or patio onto a table or shelf, even sit them on top of a cinder block. That and the diatomaceous earth should take care of the problem.