Laboratory tests determined the lateral and vertical dispersal patterns of Neoaplectana carpocapsae in sand. In the vertical tests, placement of infective juveniles 15 cm below the sand's surface resulted in the majority (77%) being recovered above the point of placement after 48 h. Placement of the nematodes on the sand's surface resulted in the majority (90.4%) remaining within 1 cm of the sand's surface. Placement of nematodes at depths of 2.5 cm and 5.0 cm below the sand's surface also resulted in little nematode dispersal. However, vertical hioassay tests showed that juvenile nematodes placed on the sand's surface dispersed 12 cm down to infect 67% of the Galleria mellonella pupae placed at the depth. Conversely, when nematodes were placed 11 cm below the insect pupae no infection was observed, but 53% infection occurred when nematodes were 7 cm below the site of the insect pupae. In lateral dispersal, 87% of the nematodes rentained within 2 cm of the placement site, although 0.5% were recovered at 12-14 cm away from the point of placement. Lateral bioassay tests indicated that the nematodes were capable of infecting 90, 35, and 5% of the G. mellonella pupae at 7 cm, 10 cm, and 14 cm from the point of placement, respectively.