The objective of this study was to evaluate the susceptibility of Bradysia difformis Frey to the entomopathogenic nematodes Heterorhabditis bacteriophora Poinar and Steinernema feltiae Filipjev, as well as the persistence of the nematodes in the substrate used for poinsettia production. No differences were found in the proportion of infection caused by the two nematode species on B. difformis (F_1,28 = 3.44, P = 0.542). However, significant differences were found in the susceptibility of larvae compared to pupae of B. difformis (F_1,28 = 1,760, P < 0.001). The type of substrate had a significant effect on the persistence of the two nematodes (F_2,94.8 = 62.83, P < 0.001). The persistence of both nematode species was affected by moisture in the substrate.