Experiments were conducted to optimize the number of Trichogramma ostriniae (Peng & Chen) necessary to control Ostrinia nubilalis Hübner in the field. Numbers of O. nubilalis egg masses/100 plants contributed significantly to the number of egg masses attacked by T. ostriniae in the field (y=0.75x – 1.48; R2=0.89; f=239.92, df=1, P=<0.0001) and approximated a Type I functional response. Laboratory cage experiments were performed using whole plants in experiments by restricting leaf area to discreet classes based on field-collected data. Leaf area did not contribute significantly to the number of egg masses parasitized by foraging female T. ostriniae wasps (f=0.64, df=1, P=0.431). Increasing the number of wasps significantly increased parasitism of O. nubilalis egg masses (f=4.66, df=2, P=0.021). Linear regression of T. ostriniae density versus O. nubilalis egg mass parasitism provided a slope of y=5.6981x – 14.748. This was used to estimate 17.0 foraging T. ostriniae females needed per plant to achieve an 80.0% parasitism rate. Experiments performed here suggest that 51.0 T. ostriniae foraging females/plant are present after the first day, decreasing to 24.6/plant by the second day and finally to 11.8 T. ostriniae/plant by day three after release. The estimates of Trichogramma necessary to achieve 80% parasitism of O. nubilalis egg masses fall into the middle of the calculated range (51.0 – 11.8).