Ants and Aphids

I just noticed a lot of aphids on the ivy which climbs up the side of the orange shipping container in my back yard. Ants tending them "farm" and "milk" them for the "honeydew" which they exude. Wikipedia explains this mutualistic relationship very well if you look up "Aphids" or "Ants".

I don't know what kind of ants or aphids these are.

I took this picture with my Pentax K20D, 90mm Tamron macro lens and my Pentax AF160FC Pentax Ring Flash, shutter 1/180 and aperture f32 for maximum depth of field.