The cell contents are able to leak from the damaged cells, and the insect quickly dies. There is no residual insecticidal activity once the spray application has dried. Benefits of Insecticidal Soap Insecticidal soaps are most effective on soft-bodied pests such as aphids, adelgids, lace bugs, leafhoppers, mealybugs, thrips, sawfly larvae, spider mites and whiteflies. Soap has a limited effect on non target beneficial insects such as ladybird beetle larvae, parasitic wasps and honey bees, but it can be quite disruptive to soft-bodied predators, such as syrphid fly larvae and beneficial predatory mites. Once the spray has dried, however, beneficial insects can safely reenter the treated area.
Soaps have low mammalian toxicity.
However, they can be mildly irritating to the skin or eyes. Insecticidal soaps are biodegradable, do not persist in the environment, and they do not contain any organic solvents. It is less likely that resistance to insecticidal soaps will develop as quickly as to the more traditional pesticides. Resistance within the insect tends to develop more quickly with materials that have a very specific mode of action. A material that affects the insect's nervous system in a very specific way has a greater chance of developing resistance in a shorter period of time.