You might spend some time watching them to try to figure out exactly what they do where they go, and what they do there. The seldom stop moving except on business. You might try to identify some kind of damage to the corn, or other nefarious behavoir and try to describe and photograph that. I used to work at a garden center, and often some plant damage was caused by one creature, and then when the gardener was watching, they see another creature walking by, and they get pinned with the crime... "I've been framed" they gesticulate with their antenna, but no one pays attention to their plea, squish... sad story.
Victor Johanson wrote:Why do anything? Are they harming the corn in any way? Perhaps there are aphids, although I can't see any in the photo. But it is certain these ants are performing some function in your ecosystem, and eradicating them isn't necessarily desirable. Unless you have evidence that they are causing damage, do nothing but observe and learn. I was pleased to find ants breeding in my hugelbeet; diversity is welcome there and plant growth is far more vigorous and healthy than in the regular garden plots.
Look at the picture again, especially the central stalk. It is packed with aphids. You may have mistaken them for droplets of water but you can see the tiny legs on some of them.