Answer: Could be wildlife - squirrels, raccoons, rabbits - or it might be slugs and snails. Look for a slime trail in the early morning, or go out at dusk and inspect the area. If you find the creatures, hand pick them. You can set a trap for them by soaking a terra cotta pot in water until it's saturated, then setting it upside down in the garden near your herbs, propping it up an inch or two with a stick or rock. Snails and slugs will seek out a cool, moist place and will collect in the pot. In the morning, scrape them out and reset your trap.
If it's not slugs or snails munching on your herbs, it might be squireels, raccoons or rabbits. If so, you can set a 2-3 foot high chicken wire fence over your herbs so the critters can't get to them.
Best wishes with your herb bed!
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