Aphids, spider mites and white flies are all common garden pests that can ruin your garden. There are numerous fogs and insecticides out there that can kill many of these creatures on contact, but many contain chemicals that you may not want to use on your plants. Dawn dishwashing liquid offers a quick fix for many pests, but may not be effective in the long run.
Dawn can kill many insects via a process known as desiccation, though the exact method with which it and other soaps kill pests is still not fully understood. Desiccation causes the insect to dry out and its outer skin literally cracks open.
Dawn liquid soap must be diluted with water in order to be effective. It is typically mixed in a spray bottle with water at a concentration between 2 and 3 percent. The combination of water covering the insect plus the desiccation brought about by the soap will remove the waxy coating from the creature, drying it out and killing it.
Dawn may also be used as a topical shampoo for dogs or cats suffering from fleas. The dead fleas must be removed from the fur with a comb.
Benefits and Limitations
Insecticides made from Dawn dish soap are readily made and inexpensive. They can kill insects on contact and generally do not harm plants provided they are not applied too often. Plants sprayed with the insecticide should be rinsed with water afterward to remove any soapy residue. However, Dawn-based insecticides do not act as preventatives. They will help reduce existing populations but will do virtually nothing to prevent future infestations.