Limiting the number of soap applications can also be important, as leaf damage can accumulate with repeated exposure. Also, application must be thorough and completely wet the pest. This usually means spraying undersides of leaves and other protected sites. Insects that cannot be completely wetted, such as aphids within curled leaves, will not be controlled. Environmental factors also can affect use of soaps.
Control decreases if hard-water sources are used.
Soaps and detergents can offer a relatively safe and easy means to control many insect pests. As with all pesticides, however, there are limitations and hazards associated with their use. Understand these limitations, and carefully follow all label instructions. Approximate mix to produce various dilute soap sprays. 1 Colorado State University Cooperative Extension entomologist and professor, bioagricultural sciences and pest management.