The plum curculio, Conotrachelus nenuphar, is a devastating pest of pome and stone fruits in eastern and central North America. An isolated plum curculio population was detected in Box Elder County in northern Utah in 1980. The main control method for C. nenuphar is applications of insecticides to kill adults. Entomopathogenic nematodes are good candidates for reducing the risk of insecticides and suppressing insect populations by an environmentally sustainable approach. However, the mortality of C. nenuphar varies by life stage and species of entomopathogenic nematode. In addition, temperature is a major factor affecting virulence of nematodes against insect life stages. We conducted three experiments to evaluate the suitability of entomopathogenic nematodes for managing plum curculio. Two entomopathogenic nematode species, a Utah population of Heterorhabditis bacteriophora and a commercially available strain of Steinernema feltiae, we compared for field efficacy in suppressing plum curculio populations in home yard fruit trees. The field efficacy varied by species. Secondly, mortality was compared for three plum curculio life stages: larva, pupa, and adult. The larva stage was more vulnerable than other life stages and speed of kill and total mortality was greater for H. bacteriophora than S. feltiae. And lastly, the influence of temperature host infectivity and mortality, and nematode reproduction on a surrogate insect host, Gelleria mellonella, was compared for the two nematode species. Reproduction was greater at 20°C than 10°C and 30°C for both S. feltiae and H. bacteriophora. However, infectivity and mortality varied across temperatures between the two nematode species.