Insecticidal soaps and pesticides that use natural ingredients are very effective in repelling bugs that would otherwise devour food crops. But remember that even natural insect sprays will rid your plants of beneficial insects, as well as garden pests. Many are not selective in the insects that they affect, so use with care, only after other natural methods of pest control have failed to take care of the problem.
Apply sprays in the early morning or evening, when temperatures are cooler. Applications made when temperatures are above 80 degrees Fahrenheit may cause foliage to burn. Test a small area and wait 24 hours with all sprays and do not increase the strength of your solution just because you are getting good results. Use sprays that target specific insects whenever possible and spray only problem areas to avoid repelling beneficial insects. Take care to protect exposed face and skin when working with sprays and dusts.
Insecticidal soaps are safe, organic sprays that repel insects. Made with liquid hand soaps and light vegetable oil and water, the soap is sprayed directly onto soft-bodied insects, such as aphids, white flies, mealy bugs and spider mites.
Many teas are selective in the insects that they repel. Parsley tea repels asparagus beetle, and wormwood tea is effective against slugs, snails, black flea beetles, cabbage moths and fleas. Yarrow tea deters mealy bugs, aphids and other soft- bodied pests. Tea consisting of horseradish root, petunia leaves, lime or chili peppers will function as a general pest repellent, but may deter beneficial insects as well.
A garlic foliar spray will deter fungus gnats, aphids, cabbage loopers, grasshoppers, June bugs, leaf hoppers, mites, squash bugs, slugs and white flies. An elderberry leaf spray will keep the garden free of cucumber beetles, peach tree borers, aphids and carrot root flies. Marigold spray repels asparagus beetles, tomato hornworms and leaf-chewing insects. A spray with orange peels deters fungus gnats, mealy bugs and aphids, and repels ants.
A powder made of ground leaves from bay, cayenne peppers, tansy and peppermint sprinkled over foilage makes an effective insecticidal dust.