Become a totally organic gardener. Since I became totally organic with my soil amendments and fertilizers the number of insect attacks has dropped to almost zero. I started this about 30 years ago when commercial organic fertilizers first came on the market. Back then it was a continuous battle with aphids, stink bugs and all kinds of beetles. I haven't seen an aphid in my garden in years. About 10 years ago I had a severe stink bug infestation for some reason but it was short-lived. The only thing that I get now are caterpillars. Hornworms, loopers, armyworms, wooly bears, all the usual and sometimes they come by the hundreds. But, they are easily contained with today's remedies. Back in the old days, all we had were dangerous chemicals like malathion and diazinon. The closest thing to today's insecticides was Sevin. But how things have changed during the past 10 years or so. Today's gardener needs only 3 products: Spinosad, Bt and Neem Oil. I still have some of each left and I bought a 16 oz bottle of each, IIRC, 4 years ago. I might have to buy more next year. And my garden is larger than most.
I think that one of the biggest problems gardeners have is either a lack of time or commitment. They do not spend enough time in their gardens observing what is happening. Usually, things do not happen overnight. It takes time for a population of aphids or spider mites or stink bugs to really become a serious threat and when they do become a serious threat it is sometimes too late or the number of insects is overwhelming. One must look at each individual plant, be it a bean plant or a broccoli, asparagus or zucinni. Each plant, both sides of the leaves and the stem must be looked at, at least every week, or those pesky aphids will sneak up and attack. And to answer your question, use either spinosad or soapy water. Aphids are easy to get rid of.
