Succulent, red, ripe, juicy tomatoes are irresistible to tomato hornworms and fruit flies. Pepper and eggplant leaves are favorites of aphids, scale insects and white flies. Although insects will find all kinds of devious ways to dine on your vegetable garden, you can control them with some simple, nontoxic recipes.
You can easily control small chewing insects such as aphids, spider mites, mealy bugs and juvenile scale insects with a solution of dish soap and water. Combine 2 tbsp. of a classic (non-ultra) dish soap with 1 gallon of water. Transfer some of the mixture to a spray bottle, which usually holds 24 or 32 oz., and spray your affected plant(s) every other day until all signs of the insect are gone. AdviceOnGardening.com says you can also add "Tabasco sauce, garlic, peppermint and vinegar." The amount you add is up to you, but in general, for 1 qt. of solution, add no more than 1 tbsp. of each of these products. Experiment with different products to determine which works best for your insect problem.
Insecticidal Soap with Vegetable Oil
Adult scale insects of many species develop an armored shell that protects them from insecticidal soap. If you add canola or another vegetable oil to your insecticidal soap recipe, it will smother these pests and also kill young insects that you might not be able to see. ABC Riverina, from New South Wales, Australia, adds, "aphids, smooth-skinned caterpillars, mites...citrus leaf miners...and even young grasshoppers suffocate when their bodies are covered with oil." To make an oil spray, combine 2 cups of vegetable oil with ½ cup of dish soap in a blender. Blend until it's mixed, then mix 1 tbsp. of this formula in 1 qt. of water. Cover both sides of the leaves and repeat your application until all signs of your insect pest are gone. Resist the temptation to use a stronger mix of this product because it might burn your plant.
Other All-Natural Solutions
To make a homemade sticky trap for white flies and other flying insect pests, paint an old pane of glass or sturdy piece of clear plastic that's about 4 by 6 inches yellow. After your paint dries, smear a thin layer of auto motor oil on the side you did not paint. Place or hang the trap near the plant that has been bothered by the insects. Once a month, wipe the oil off the glass and replenish it with fresh oil. You can use these traps inside or out.
Hand picking and sanitation are other natural methods for controlling certain insects. Hand picking is simply the act of picking up an insect with your fingers and destroying it by squashing it or placing it in a substance that will cause it to die. Hand pick scale insects and mealybugs.
According to the University of Colorado, "Seriously infested plants are often best discarded because they usually require lengthy and extraordinary efforts to control the pests. They may also serve as a source for infesting other plants." In general, keep dead leaves, flowers and other plant materials cleaned up around your plants, especially if they might contain insects or their eggs.