Before you haul out the pesticides to treat a plant, think about what you are doing first. Plants with insect problems usually means the plant is stressed out. If you do not treat the underlying problem first, you are wasting your time and poisoning the environment.
Stressors include over or under watering, the wrong species in the wrong spot, an exotic species for your soils and climate, or even root disturbance such as excavation under the canopy of a tree.
Insects are also attracted to well-fertilized plants. This might sound odd, as who doesn’t think a happy plant is one that is growing fast and furious? The reality is plants growing too fast sacrifice their defense against insects and disease. A much happier plant is one that has moderate growth. If your plant is doing well, don’t fertilize it.
So what to do with the insects? Get out the hose and spray them off. It is amazing how many insects hate to get wet.