Introducing predatory insects like ladybugs and lacewings into a particular environment is an effective way to eliminate aphids. Horticultural oil, alcohol spray and natural insecticidal soap can also be used to control aphid infestations.
A natural insecticidal spray can be made with a quart of water, a teaspoon of liquid dish soap and a small amount of cayenne pepper. Another option is to blend five parts water, two parts rubbing alcohol and a tablespoon of liquid soap.
Spraying the plant daily with a strong stream of water removes aphids and also eliminates the honeydew that they feed on. Planting onions or garlic near the infestation is another natural aphid deterrent.