Yes ants "milk" the aphids. They prevent lady bugs and other Aphids eats from getting to the Aphids. Spraying down your plants with water really helps getting Aphids off, sometimes I likes to use those office dusters. They work great. If that does'nt sound good you can get some soapy pesticides and spray your habs down.
hope this helps!

I found that if I get rid of the ants the aphids don't last long without them outside.
I put boric acid powder and D.E. around my pots/Plants and it keeps the bugs that crawl away from my plants.
I use Terro brand Ant killer and it kills off the colony.
Woodstream makes ant bait too but it doesn't work as well for me.
Aphids spread diseases,get rid of them if you can.

Lacewings are great for getting rid of ahids - better than ladybugs in my opinion.They overwinter here and I have a lot around from last year.
You'll never get rid of the aphids if you don't handle the ants first.They farm the aphids.
They help spread them around so they spread from place to place quicker.
I read they even take some underground to feed on roots so they can eat the honeydew from the aphids.

I have Syrphid flies (hover flies)and some kind of parrasitic wasp here naturally and they also help with aphid control.
The adult feeds on the honeydew and pollen and they lay eggs in the aphids that hatch and eat the aphids from the inside out.
If you see a lot of large silverish aphid mummies with holes in their butts thats because the syrphid fly larva ate its way out and left the dead aphid.
For some reason the aphid gets bigger when it has a parrisite in it.
Look at the large aphid and you'll see it has a black thing in it's backside.The aphid will start to get brown instead of green.Then it'll be a silver brown with the hole in its butt where the larva came out.

Syrphid flies look close to what a yellowjacket looks like.There are several kinds.The ones here are silver and black striped.Some are white and black striped and others yellow and black striped.Google Syrphid flies if your interested.
There are some that the larva turns into a caterpillar looking thing that eats anything it can catch.
I've seen them too.
They look like caterpillars but have little hair like things-feelers on their heads and are allways checking out the undersides of leaves for bugs to eat.
The caterpiller type makes a green cacoon on top of leaves,not hanging down that hatches into a fly.
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Aphid Mummy & Aphid Parasite
Hymenoptera: Aphidiidae

Identification
These small, blackish wasps are Host Range
 Each aphid parasite species attacks only a few aphid species and they will not attack any other (nonaphid) group of pests.

Life Cycle
 A female wasp lays a single egg in an aphid. After the egg hatches, the parasite larva feeds inside the aphid, where it pupates. Newly emerged adult parasites exit from the aphid body.
 The dead aphid (mummy) has a bloated appearance and is brownish or white.

Other Information
 While the parasite is seldom seen, results of its actions (aphid mummies) are easily viewed in most aphid colonies.

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aphid mummy

http://woodypest.ifas.ufl.edu/251.htm

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Hover flies

http://www.cirrusimage.com/Flies_hover.htm

http://bugguide.net/node/view/196/bgimage

Probably more than you wanted to know. LOL
I had this stuff bookmarked from when I was looking for a solution to my bug problem.

Smokemaster you mention "Boric acid and D.E." around your plants. What is D.E.?

Thanks alot,

Ravi

D.E. is dichotomous earth. It's a natural powder that creates a pest barrier.

Umm. Not "dichotomous earth" but diatomaceous earth.

Thanks guys.

Ravi

All my plants are on asphalt so I sprinkle it on the ground then put my pots on it(D.E.+Boric Acid).
I've read that Boric Acid can Bleach stuff so if your pots are on a deck or on cement you might want to test it first.
I have to put more down every so often after it gets washed away from watering my plants.
Too much boric acid can turn your soil acid too.I've never had that problem though but I always put Dolomite Lime in my potting mixes for calcium-peppers need it when they flower.

Here is what I use, (See link) and I use the food grade as it's totally safe for human consumtion.

The only other thing I like is Safer soap spray for the aphids.

1 TBSP of Octagon dishsoap/baby shampoo/horse shampoo in a gal of water will kill the aphids on contact

cut way back on your nitrogen fertlizer helps too

Thanks for all the input on this question/comment.
I guess what I'm getting at in this post is that when I put the plants in the ground and the ants came, there are NO APHIDS to be found on any of my plants now. Did the ants take them underground for milking or what?
All I know is that I now appear to be aphid free!!!!!

There might be aphid eating bugs outside that aren't inside or wherever you first grew them.
I always have aphid problems with indoor plants and little to none outside as long as the ants are under control.
If ants were farming them you would have a lot of aphids because the ants raise them and protect them from getting eaten etc.
Maybe there was a starving Mantis,Lacewing or ladybug just waiting for you to take the aphids outside to play. :)

You know that some ant species transport aphids to new plants and some even keep the aphids in their nests. Some even dig under the plants and put aphids directly on the roots to suck out the juices.