We investigated the dispersal ability of Trichogramma ostriniae Pang et Chen (Hymenoptera: Trichogrammatidae), a biological control agent of Ostrinia nubilalis (Lepidoptera: Crambidae) in commercial potatoes. The purpose of the study was to quantify dispersal of T. ostriniae after an inundative release to aid in determining the number of release points needed per unit area for effective biological control of O. nubilalis in solanaceous crops. A single release was made in two spatially separate potato fields on the Eastern Shore of Virginia in summer 2005 and 2006. From a central release point, dispersal was measured over a ∼ 0.4 ha monitoring area. Each area contained 25 monitoring points at distances from 5 to 45 meters from the release point bearing a yellow sticky card and O. nubilalis egg sentinels to observe for adult wasps and parasitism, respectively. Results showed that T. ostriniae dispersed quickly up to 45m within 4 days in 2005 and 1 day in 2006. High rates of parasitization were recorded at this distance (20-50%) and decreased with increasing distance. The greatest numbers of T. ostriniae were recovered within 3-4 days of emergence Averaging the mean distance encompassing 98% of wasps for all fields, the majority of wasps dispersed within ~ 17 meters of the central release point. Based on these results multiple release points per 0.4 ha (or 1.0 acre) should be made for effective dispersal of T. ostriniae and control of ECB in solanaceous crops.