Use Insecticidal Soap

Spray affected plants thoroughly with insecticidal soap to kill soft-bodied pests like aphids, spider mites, and whiteflies. Ensure complete coverage of all plant surfaces, especially the undersides of leaves where pests congregate. Repeat applications every five to seven days until the infestation is under control. Use commercial concentrate mixed according to label directions, or a ready-to-use formulation.

Why It Works

Insecticidal soap contains potassium salts of fatty acids that penetrate and disrupt the cell membranes of soft-bodied insects, causing rapid dehydration and death. The soap must make direct contact with the pest to be effective -- it has no residual killing action once dry, which also means it poses minimal risk to beneficial insects that arrive after application.

Tips

• Test on a small leaf area first, as some plants (ferns, sweet peas, new transplants) are sensitive
• Apply in the early morning or evening to reduce leaf burn risk
• Do not use household dish soap as a substitute -- it can damage plants
• Reapply after rain since dried soap has no residual effect
• Avoid spraying during temperatures above 32°C (90°F)