Early stand decrease in alfalfa (Medicago sativa L.) throughout New Mexico is increasingly being attributed to root systems damaged by larvae of whitefringed beetle, Naupactus leucoloma Dejean. Entomopathogenic nematodes (Steinernema carpocapsae Weiser, Steinernema feltiae Filipjev, and Heterorhabditis bacteriophora Poinar) effectively control other species that inflict similar damage to alfalfa and other crops, but it is not known if they occur naturally or can persist if released in irrigated semiarid lands. Persistent strains of entomopathogenic nematodes were released in May 2017 by the New Mexico State University Rex E. Kirksey Agricultural Science Center at Tucumcari into an irrigated alfalfa field not known to be infested with whitefringed beetle. Treatments were mixtures of nematode species Steinernema carpocapsae (NY 001) + S. feltiae (NY 04) or S. feltiae (NY 04) + Heterorhabditis bacteriophora (Oswego) in a randomized complete block design with four replications near nontreated check plots. Twenty soil cores were collected per plot in autumn 2017 and 2018 to bioassay for establishment of entomopathogenic nematodes. After inoculation, S. carpocapsae was not found in any sample either year, while H. bacteriophora was found only in 4% of samples from S. feltiae + H. bacteriophora plots in 2017. Similar percentages of S. feltiae were found each year (∼20% of cores in S. feltiae + S. carpocapsae and S. feltiae + H. bacteriophora plots). No entomopathogenic nematode was detected in nontreated check plots, suggesting lack of native entomopathogenic nematodes and lack of spread from treated plots. The multiyear persistence of S. feltiae ‘NY 04' and perhaps H. bacteriophora ‘Oswego’ in the arid Southwestern US was not reported previously. Because entomopathogenic nematodes can control whitefringed beetle and a plethora of other crop pests with similar larval root-feeding behavior on many economic crops, establishing locally adapted sources of entomopathogenic nematodes for widespread distribution would be appropriate.