Earwig infested corn
The traditional and organic way to reduce earwigs is to put an upturned flower pot on top of canes or sticks near the plants and stuff the pots with newspaper. This attracts the earwigs into the pots and takes them away from your plants. However, it might be a bit late for this in your case, so I would suggest you just clean the cobs when you open them and then put the flower pots in place for your next crop. It is difficult to control them with sprays if they are already in the crop. I hope this helps.