There are many different solutions given for this problem. You could use a pesticide but that does more harm than good as you will wind up killing all the beneficial worms and insects in your garden. I have used styrofoam cups with the bottom half cut out to use as a ring around the plant. Aluminum foil wrapped around the base of the plant will also save them. I have been told that a nail placed beside the plant stem will not allow the worm to wrap completely around the stem and will not eat it. Each one is time consuming, but I have found that a simple cardboard tube about 4 inches tall and 4 inches in diameter, placed around the base of a young plant will stop 95% of the cutworms from killing your plants. Another bonus is if you use the right cardboard, it is biodegradable and you can just till it under in the fall. See the related link for more information.