ants tending to bugs on my orange tree

I have this dwarf orange tree in my yard (SF bay area in CA). Last year during the summer and recently this year I noticed that at the very top of the plant (end of highest branches) there was a cluster of small black bugs and they were being tended to by a stream of ants (they did not look like ant larve).
What are these bugs?
Do I need to get rid of them vigorously? (they don't seem to be causing much plant stress)
Are they aphids (they look larger and blacker than what I thought)? Do I remove the effected leaves to evict the bugs or do I control the ants?
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snipped-for-privacy@earthlink.net says... :) What are these bugs? :) :) Do I need to get rid of them vigorously? (they don't seem to be causing much :) plant stress) :) :) Are they aphids (they look larger and blacker than what I thought)? Do I :) remove the effected leaves to evict the bugs or do I control the ants? :) Probably aphids..if they aren't out of control you probably could just use a stream of water form the hose to remove them.
--
Lar

to email....get rid of the BUGS
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AutoTracer wrote:

The ants are protecting aphids from ladybugs and other predators. The ants will even move the aphids to new growth. You must control the ants even if you are otherwise successful in eliminating the aphids.
--
David E. Ross
Climate: California Mediterranean
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Aphids come in most colors of the rainbow, I have seen green, black, white,orange and yellow. You have most likely aphids. Blast em with water. Use hot pepper wax Use insecticidal soap Rub em dead with your thumb
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