Vegetable gardeners can make their own sprays to ward off insect pests. Alternatively, the National Sustainable Agriculture Information Service maintains a database of options, including commercial products, for specific pest and insect problems.
According to Mother Earth News, mixing a teaspoon of liquid detergent with a cup of vegetable oil and a quart of tap water will make a spray that can help cope with whitefly, spider mites and aphids on vegetables in your garden. The spray should be applied directly to the insect pests. Pyrethrin is a common organic insecticide derived from the pyrethrum plant and available from a number of different companies and gardening stores.
Soapsuds works against aphids in vegetable gardens. Some gardeners mix garlic and onions and then strain the mixture to make a spray they can apply to control insect pests. According to Mother Earth News, spearmint spray concentrate blends a cup each of chopped spearmint and green onion tops, a half cup of red hot peppers mixed with water and a half cup of liquid detergent.