Below are links for online sources for three topics important to biological control. I have vetted the links, they are useful and valid sources of information.
Know the Rules of Ecology
The website of Alexei Sharov: http://alexei.nfshost.com/PopEcol/lec1/whatis.html
Basic (very) Introduction to Ecology:
An interesting aspect of the larger ecological concept of symbiosis. Mutualism has an important role to play in how well biological control works for homopterous insects that produce honeydew.
Know How to Identify the Organisms
Key to Hymenoptera:
UC IPM Natural Enemies Guide - California:
Interactive Insect ID Key:
Key to Heteroptera - PDF:
Key to Diptera Families from Britain (still useful in CA):
Know How to Validate Resources and Actions
UC IPM is an invaluable resource for beginners as well as seasoned practitioners:
Koppert, Inc. is an excellent company that provides substantial information for end users to ensure product quality and performance: