Certain earwigs are predaceous, and will eat other small garden pests. They are also known to eat decaying plant matter, which helps in composting the garden soil. But some types of earwigs also love living plants, and thus can be quite the pests, especially to young plants and seedlings.
The earwigs in our yard here in Reno seem to be the young plant loving types. This year, they have taken to eating all of our beet sprouts, keeping the beet greens nibbled down practically to the ground. They are also eating the kale leaves, but the kale grows so fast, the earwig nibbles don't seem to harm the plants overall. They seem to leave the nightshades like peppers and tomatoes completely alone. They will eat all sorts of flowering plants, too. We've given up trying to grow lobelia in our garden since in past years, earwigs would literally strip the plant of all vegetation within one or two evenings. We've thought about using lobelia as a sacrifice plant, but wonder if we would simply be inviting the insects to stay.
Earwigs are nocturnal, so you won't see much of them unless you suddenly expose them to sunlight. At night you can go into the garden with a flash light and catch them in the act. Squish them when you see them. Don't worry about the pincers. They don't bite or sting, and only the large males might pinch, but very rarely. They are much more inclined to scurry away when seen. Squish them in you can! Or squirt them with soapy garlic water.
A sure way to greatly reduce your garden's earwig population is to dust the ground just before nightfall with diatomaceous earth. Diatomaceous earth is not a chemical pesticide. The non-poisonous powdered rock acts as an abrasive which dries out the earwig's body, which kills them. You can pick up diatomaceous earth at Dry Creek. The stuff works wonders.
To make your own garlic spray, smash a couple large cloves of garlic with a tablespoon of mineral oil and a squirt or two of liquid dish soap. Let the mixture steep, then mix with a pint of water. Strain well, then fill a pint spray jar with the liquid. If you're worried about burning your plants, you might want to test your spray on a leaf or two. Once your garlic water is ready, go out at night, find them and squirt them! It's fun to catch them by surprise and to watch them fall from the plants.