Grubs in the soil will eat plant roots, but they don't climb above soil level to feed on the leaves. Some other pest must be feeding on the aboveground parts of the plants. (Also, plants can tolerate quite a bit of root feeding by grubs. Generally, unless your garden has more than 5 or 10 grubs per square foot, you don't need to treat for them.)
You can control chewing insects on the foliage with one of several products. Spinosad is a natural, bacteria-based insecticide that has organic certification. Other conventional pesticides such as carbaryl (Sevin) should work, too.