Once it is identified, information about the pest's biology can be used to identify the weak points in its life cycle when suppressive measures will have the greatest effect. The next step is monitoring the pest populations. This is crucial to IPM because it provides the information needed to make decisions about the timing of treatments and whether or not they are necessary. Most monitoring programs are based on a regular inspection for pests or signs of their presence. Pest managers use a variety of methods, such as visual inspections and counts of insects caught in traps or in sweep nets.
Growers often find that just by instituting a monitoring program they use fewer sprays.
For example, B.C. apple growers who monitor the codling moth numbers in their orchards with pheromone traps, spray only after a predetermined number of moths are captured in a trap. For most of the carrot acreage, the resulting level of insect control was about the same as in previous years. The third component of an IPM program is the determination of an unacceptable amount of damage, or injury level, for a particular pest. In agricultural crops this is usually an economic injury level. How much damage is tolerable depends on what part of the crop is affected, the cost of the treatments and the value of the crop that would be lost if not treated.