As my Concord Grape vine grows I've found that aphids have started occurring on the tips of the new growth. Concord Grapes are not one I recommend, unless you're experienced with canning and making jam. They taste exactly like jelly right out of the jar.
The ants here are Camponotus nearcticus is the ant species looking over the aphids. Notice how the major worker above is so full of honeydew that her gaster has expanded to become transparent in places. The soft membrane under her exoskeleton stretches out to allow for more room. Major workers are often used as food carriers in the colony as they can hold a greater capacity than their smaller counterparts.
This isn't an infestation by any means. Along the entire vine that stretched around our entire back deck I was only able to find two clusters of them. I'd be worried if they were infesting places where the plant was fruiting but so far that's not the case. At their worst aphids tend to only hinder 15% of the year's growth. Some species can cause feather problems by raining down honeydew all over the plant, allowing diseases to spread easy, but this isn't one of them.