Corn pests

[Quickening]

I've noticed that there is a certain kind of pest that is crawling and flying around the corn crop in the garden. I don't see them on any other crop, just the corn. Does anyone know what they could be? They have reddish orange sort of bodies black legs etc. I will take photos when it finishes raining. There are also yellow spots here and there on the leaves too, the corn plants are no longer looking lush and healthy. I also noticed little black ants on the plants as well.

[Momtezuma Tuatara]

When I plant corn, a huge amount of compost goes in. corn is a heavy feeder. (american tribes used to put one fish under every corn plant)

You've had a lot of rain, so are the spots an orangy colour sort of streaky? If so, they could be corn rust. As to the legged specimen, don't know about aussie pests :D