Insecticidal Soap is defined as any of the potassium fatty acid soaps used to control many plant pests and diseases. This product is typically sprayed on plants in the same manner as other insecticides. It works only on direct contact with the pests. The fatty acids disrupt the structure and permeability of the insect cell membranes and the insect quickly dies. Soaps of this kind also work well on fungus infections such as botritis and leaf spot as well as on common houseplant pests such as spider mite and mealy bug.