During the last three years considerable time has been devoted to the development of a technique for rearing larvae of the European corn borer, Pyrausta nubilalis Hubn., in quantity. This work nas necessary for the breeding of parasites working on the first instars of the borer, such as, Microgaster tibialis Nees which has been reared successfully during the last two years, Eulimneria crassifemur Thom., Macrocentrus gifuensis Ashm., and Apanteles thompsoni Lyle, work with the last three species being still in the experimental stage. Though large numbers of larvae can be produced by employing the methods outlined in this paper further experiments are in progress with a view to reducing the larval mortality, particularly in the second and third instars.