Swiss Chard is a favorite of slugs, snails and some flying pests. To keep the slimy critters away use a pet and food safe slug bait such as Worry Free or Sluggo. I also set out strips of wet cardboard in the spring and collect the tiny baby slugs and snails that hide during the day under the cardboard. To keep green worms and the larvae of other flying insects off the greens cover the plants with a floating row cover of Remay or agricultural fleece. This lightweight cloth allows sun and rain but not the flying insects.  At least you can still eat Swiss Chard with a few holes I the leaves. Dunk it in salt water to remove any unwelcome stowaways before cooking. Keep growing, Marianne Binetti