One of a three-part series, this bulletin presents techniques developed at CIMMYT and used over the past six years for efficient mass rearing and infestation with the corn earworm-Heliothis zea (Boddie)-for screening and development of host plant resistance to the insect in maize. The author explains techniques for establishment of the insect colony, gives basic requirements for efficient mass rearing, describes a method of efficient field infestation, and covers rating scales used to evaluate damage and identify resistant genotypes.16 pages