I always thought soapy water was the recipe for controlling bugs on tomatoes and peppers but it turns out soap is not just soap. I'm researching because my usual dish soap and water mixture this year is not working and I may have lost my tomato plants early.
An insecticidal soap is a potassium fatty acid soap (aka -- natural) as opposed to a synthetic detergent. It's much more like what would have been made in the home 150 years ago before chemical engineering designed something that will clean better. These old timey soaps work well for simple dirt but not well for stains. Here are a few that are considered insecticidal ---- Zote, Fels Naptha, Roma, Dawn(?)
Insecticidal soap works best on soft-bodied insects and arthropods such as aphids, adelgids, mealybugs, spider mites, thrips, jumping plant lice, scale insects, whiteflies, and sawfly larvae.
Combining insecticidal soap with water makes a concentrated form of insecticidal soap spray. In order to make the concentrate, grate about 1 inch from a bar of Zote soap, put the grated soap in 1 quart of warm water and stir the water gently until the soap dissolves. The concentrated solution should be stored in a clearly labeled container. When you're ready to spray your plants with an insecticide, place 1 quart of water in a spray bottle or garden sprayer, and add to it 1 teaspoon of the Zote concentrate you made. Don't use a stronger solution. Although insecticidal soap spray is safe for most plants, a high concentration of it may damage plant foliage.
Whitefly damage - worse year so far
Shaving pieces off a bar of Zote
Soap dissolving in the sun
........ Simple video for the idea ......