Reply #1: I have never tried this, but it is organic and sounds like it should work.

[Arkansas Granny]

A recipe for a home remedy to get rid of aphids
1 cup vegetable or white mineral oil
1 1/2 cup water
2 teaspoons dish soap or Murphy’s soap

Spray this homemade aphid control mixture on the aphids every few days until the aphids recede. This home remedy to get rid of aphids will suffocate the aphids.

http://www.gardeningknowhow.com/problems/homemade-aphid-control-a-natural-way-to-kill-aphids.htm

They also have some other methods of controlling aphids on that page that you might find helpful.