Information provided by Whitney Cranshaw, Colorado State University Cooperative Extension specialist, entomology
Soaps have long been used for control of insects and mites. Several "insecticidal" soaps are sold at nurseries and through garden catalogs. These soaps control a variety of garden pests. In addition, some soft hand soaps and liquid dishwashing detergents can kill insects. In general, soaps tend to kill small, soft-bodied insects and mites, such as aphids, newly hatched scales (crawlers) and plant bugs.
Insecticidal soaps are used as dilute sprays, typically at a 2 percent dilution -- or about 2 teaspoons per pint. Their advantages are a high degree of safety to the applicator and other "non-target" species, minimal adverse effects to beneficial insects and ease of use. Soaps also have some limitations:
Soaps work best when applied in soft (or softened) water, preferably during cooler periods when drying is slowed.
Photograph courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010