Beginner Gardening: What are these bugs, 1 by AceBug

AceBug wrote:
Mammoth sunflower underside of lower leaves, that have had yellow rusty spots for at least a month, now those leaves covered in these thingies...and there have been ants on it since it started growing. I do not think any of these things are ants now though...it is as if it is an insect in varying stages of growth, the biggest ones being the light colored with brown, and have legs and all. The littlest look like ants kind of, and the others look...bigger black like they are covered in stuff or something or I suppose just haven\'t turned light colored yet.