Controlling whiteflies is difficult, and repeated sprays will be needed. Avoid plants such as fuchsia that are favored by the insect. Soil insects are noticed when brought to the surface during watering. Adults and larvae of several insects may fly or crawl around on the soil surface. In most cases, they do no real harm to the plant.
Large populations can cause wilting and poor plant growth due to minor root pruning.
Unfortunately, pesticides used to control soil insects may be as harmful to the plant as the insects. Fungus Gnats are small nuisance insects that lay eggs in plant soil, which eventually grow into more gnats. In great numbers they can become quite a problem. They can be pretty difficult to control if you let them spiral out of control, so it's best to try to detect them early on and take care of the problem before it explodes. While the organic soaps and sprays are safe and pretty much odor-free, sometimes a plant is just too far gone to be saved, Warren said.