I can tell from looking at the picture that you are not using a sufficient amount of DE. The leaves should be coated with a fine light powdery film.
Since I have used the Permethrin, DE and Dawn mix I have been able to control all my aphid problems. It does not control the whiteflies as well but it will slow them down. I used an oil spray on them also but it lasted no longer than the other mix even withe Permethrin added. For whiteflies on my cucumbers which I have in abundance I keep a sprayer with just Dawn and Permethin in it and spray them every two to three days making sure to blast the undersides of the leaves. This kills the ones it contacts but the problem will return in a few days so I just spray again. I think they will be here til colder weather moves in.
Bill
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