Are you sure that the damage is from cut worms? They don't usually bother bigger plants. Every time that I've ever had a problem with cut worms, I just place a small, perhaps quarter inch stick, in the ground right up against the base of the stalk. Have never had a cut worm to damage a plant with such a stick in place. I think that the stick disrupts the worms habit of curling around the plant and munching. Have never seen a larger plant severed by a cut worm either, I asume for the same reason, the worm can't curl around the fat stem. Do your squash have cleanly severed stems near the ground?
Eclectic gardening style, drawing from 45 years of interest and experience. Mostly plant in raised beds and containers primarily using intensive gardening techniques.