To kill insects in the garden, one recipe is to mix a concentrated solution of one cup vegetable oil (any kind) with one tablespoon of regular dish washing liquid in a container with a lid. Shake well, and shake frequently as you use it. Take four teaspoons of this concentrate and mix it with water in a two pint spray bottle. Use this to spray both top and bottom of plant surfaces. Only apply this when the outside temperature is under 85° F. If it is very hot out the mix may damage tender plant tissues.
There are strategies to prevent the insects in the first place. Various plants repel the pests that prey on other plants. If you Google “companion planting” you’ll find several links to charts about plant companions. Here’s one for instance: http://www.motherearthnews.com/organic-gardening/companion-planting-guide-zmaz81mjzraw.aspx
Marie Brack is the author of Frugal Living for the 21st Century: Adventures in Using Your Money Wisely. It’s available on Amazon.com in both Kindle and paperback versions.