The biological control of pests can involve several different types of procedure. In classical biological control (a), non-indigenous predators, parasites, pathogens or herbivores are typically, although not always, collected in the native habitat of the pest. The organisms to be released are quarantined to address biosafety concerns while non-target-host testing and other tests take place. Introductions can involve large numbers of individuals in one environment or smaller numbers in several different habitats or localities. After establishment, the introduced species and the pest are both expected to persist indefinitely at low numbers, which provides long-term control. This method is suitable if long-term persistence is desired and if non-target risks are low.

In inoculation biological control (b), the organisms are intentionally released with the expectation that they will then multiply and control the pest species for an extended period, but not permanently. The organisms reproduce after release, but establishment is neither expected nor desired. For this reason, this method is well suited to ecosystems that are periodical or contained, such as glass houses. Because establishment and long-term persistence do not occur, the procedure must be repeated regularly.

In inundative biological control (c), the organisms to be released are reared, often commercially, to increase their numbers before release and control is then achieved exclusively by the released organisms themselves. In contrast to inoculation biological control, reproduction is not expected after release — this distinction is often important for regulatory agencies. Of course, unexpected inoculative effects might occur if reproduction does take place after release.

In conservation biological control (d), aspects of the habitat or cultural practices are altered to increase the number or efficiency of predators, parasites, pathogens or herbivores. Such alternations might include providing increased spatial complexity of the habitat, for example through providing further crops, or changing the timing of various aspects of cultivation or other means of pest control, such as pesticide applications. When indigenous natural enemies are involved, this method presents limited risks to non-target hosts.