The aphid tending ants here are the average size ones, what I call "picnic ants". I had to move all my non-tomato veggies outdoors because these sneaky creatures got in and set up aphid farm on the lettuce. I'm not sure what the favorite bait is for these. Put some 'Ant B Gone Max' drops out but does not seem to have stopped them. They are super furtive and run like blazes if I come anywhere near them.
We do also have tiny black ants here (what I call "pin ants") which turned out to be really bad news because they are actually chaperones for the giant queen carpenter ants. They blaze the trail, chomping on wood and enlarging the tiniest holes to let the big ones in. I was astounded when I learned that the pin ants and regular (very large) carpenter ants were all the same species.
If the aphid ants also have these little 'chaperones' I don't know. Hope they aren't wedding planners, for your sake.
I've never had a huge problem with aphids on tomatoes. Minor problems here and there but tended to solve itself, I think maybe tomato plant is somewhat toxic to them. I'm hoping so!