Moreover, soaps were once common weapons for combating insects. They recently have been revived and are in use again. They are not harmful to humans, unless it gets in one's eyes. This type of biological warfare affects the outer membranes of insects, which makes the bugs asphyxiate. These soaps also may affect the nervous systems of the insects.
Soaps are biodegradable, but break down rather rapidly.
This is why soaps must be used frequently, perhaps every other day. Pesticide Menu Oil Horticultural oils have been used successfully for many hundreds of years. They work by suffocating the bug and killing it. As a result, the bugs cannot develop an immunity to it. A big benefit is that they do not harm people or the environment.