Reduviolus roseipennis(Reuter) spatial location and searching activity on cotton, and effectiveness in reducing numbers of 1st-instarHeliothis zea(Boddie) larvae on cotton were studied in the greenhouse and laboratory. Spatial location of adults on plants was mainly confined to the upper ⅓ of the plant on the lower surface of leaves. Predator activity, which suggests searching on plants, was crepuscular and peaked at 7:00 p.m. (CDST).First, 3rd, and 5th instar nymphs consumed 1.9, 7.9, and 38.2 larvae per day, respectively. Feeding by adults decreased with age; females consumed more hosts than males.Feeding effectiveness decreased significantly (P= 0.05) (as indicated by percent available prey consumed per predator) with an increase in number of predators. However, effectiveness was not significantly affected by an increase in number of prey. Individual predator effectiveness decreased with increased plant age and size.