Nearly all damaging insects in your garden have natural enemies. The most effective treatment is to provide an environment that attracts these predators. Some of them are familiar such as lady beetles and lacewings. Others, such as tiny parasitic wasps, may not be well known but are very important to the health of your plants.
Insecticides, when they are needed, must be chosen carefully so that they target just the pest and not the beneficial insects.
Where to purchase beneficial insects
Source:
http://ipm.ucanr.edu/QT/beneficialinsectscard.html