Trap Crop As Early Warning Device
Sunflowers can be planted as a trap crop. Plant them ten to fifteen feet away from the vulnerable crop. Keep a close eye on the stalks of the sunflowers. As soon as you see damage on the sunflowers you know to treat the vulnerable crops right away before the borer gets out of control.
If you see telltale holes and ``sawdust'' castings (excrement), slit the stalk just below the hole and pluck out the worm with tweezers.
Old pantyhose can be used to cover corn ears. It dries off quickly after rain and doesn't hold heat.
Intercropping or Companions
Intercropping with peanut or soybean seems to reduce corn borer numbers, possibly by encouraging predators and making it harder for the borers to locate the corn plants.
Try Buying Beneficial Insects
If you have a big corn crop and a bad infestation of borer, then perhaps buying beneficial insects might help. Predatory nematodes are probably the best choice though green lacewings, lady bugs and the Braconid wasps all kill borers in one manner or another.