You will need:
1 cup vegetable oil
1 table spoon full of liquid laundry detergent (not concentrated, not citrus based)
Water as needed
1 pint jar, mixing bowl, spray bottle
Mix the first 2 ingredients and pour into in a jar. Now, mix 1 to 2 tea spoons of this mix with 1 cup of tap water. Pour it into a spray bottle.
Use your insecticide in the early morning on a dry non-windy day. Shake the content of your bottle and spray the plants preferably under the leaves of the infected plants. I always get so enthusiastic and I spray the entire plant.
I have used this recipe for over decade now on my roses and tomato plants (now herbs, too!) and it always works for me.