Previous research with different species ofTrichogrammahas indicated that the size or species of the host egg in which the parasite develops may alter its efficiency (Salt 1940, Marston and Ertle 1973). Also, storing ofTrichogrammapupae at reduced temperatures weakens the emerging parasites (Schread and Garman1934). Since the host used to rearTrichogrammamay greatly affect the rearing costs, and since cold storage of pupae may ease handling of the parasites for field use(Stinner and Ridgway, unpublished data), information was needed about the effects of these factors onTrichogramma. Therefore, we conducted laboratory and field studies on the longevity, fecundity, and searching ability ofTrichogrammareared on 2 hosts and stored at reduced temperatures.