A variety of Trichogramma species are mass reared and used for inundative releases in different agricultural crops and forest systems. Mass rearing of Trichogramma for inundative releases tends to select for populations that perform well in the laboratory under optimal conditions but not necessarily in the field. It is important to develop and implement quality control procedures to detect changes in attributes that affect host searching. Flight by Trichogramma can be divided into short, local movements and long-distance flights. The effectiveness of Trichogramma used in inundative release depends largely on the distribution pattern within the crop and on the plant. The distribution of host eggs within the crop, on the plant, and between plant parts affects the probability of host encounters. Inherent attributes that determine performance or quality of a Trichogramma species or strain in a specific crop/pest situation are influenced by mass production conditions.