How to Control Worms in the Young Corn

My daughter is growing sweet corn (quite late in the year, true). It has been being chewed on (more like devoured) by critters of some sort. She found today tiny green worms that look suspiciously like Army Worms in the grass and soil below the corn today. We will consider for the time that it may be Army Worms in a very small stage. What is the best way to control this pest at this point? Needless to say, we will not be using chemical control.
Thanks