Dish soap and water is one that I have heard of also. The context of that discussion was keeping them off roses in Utah. I haven't tried it, but can attest that aphids in Arizonalove cauliflower. Now, for one I have only heard of once...
At a lecture on the wonders of whole grains and the evils of white flour (not intended to start a new subject or express my own view, just giving context of the lecture), she told us some very interesting stories to make her point. One had to do with killing roaches. She mixed the roach poison with whole grain flour and they ate it up. Her neighbor used white flour to mix with the poison and couldn't get the bugs to touch it. She also said her son in South Texas (this lecture was in Utah) used white flour in a sprayer thing, and doused his garden with a mist of white flour...and that it worked like a charm to keep the bugs away. Now, she was clearly trying to make a point to avoid white flour, which does have some merit, however, I am not sure how much she might have exaggerated her stories to make her point. That said, I have always thought that white flour as a bug deterrent in the garden was a great idea...if it worked. If anyone has any info on this, I would be most interested.
Holly