Try this.. it worked on my beets... I used a full bottle of cheapest hottest hot sauce I could find, put it in a blender with hot water to make about 1 quart. I strained it thru a coffee filter and put it in a spray bottle. I sprayed the foliage with it...They came back one more time AND NEVER BOTHERED MY BEETS AGAIN. So with the corn, spray it on the emerging ear and surrounding foliage... once they get a bite of the hot stuff they will not come back.. and it washes off for humans.
Or you can use oil instead of water. I had luck with the water so did not need to use the oil. If they come back use the oil with the hot sauce.