Tests used to monitor the quality of laboratory-reared insects must be reproducible, economical and simple if they are to be widely applied. A standard of quality must be established with which the laboratory-reared population may be compared. The wild insect of the species being monitored is deemed to be the best standard even though its application may often be difficult.Comparisons of the wild-standard and laboratory-reared insect populations (monitoring) should include those components of the biology and behavior of the species which are most important to its survival. These components are identified as life history, dispersal, survival, locating of mating sites, courtship and mating, oviposition and larval survival. Each component in this sequence is composed of identifiable traits which are subject to monitoring. The possible sources and types of variation in these traits, the means by which the variations have been measured, and the ways in which the experimental processes have been reduced to simple monitoring systems are discussed in this review.