In laboratory bioassays Steinernema riobrave Cabanillas, Poinar and Raulston (355 strain), S. carpocapsae (Weiser) (Mexican 33 strain), S. feltiae (Filipjev) (UK76 strain), and Heterorhabditis bacteriophora Poinar (HP88 strain) were all capable of infecting and killing the desert subterranean termite - Heterotermes aureus (Snyder). At 22oC, significant mortality (Ан80%) of worker H. aureus and was caused by S. riobrave, in sand assays. Body size variations of the three nematodes Infective Juveniles (IJs) have been noticed after emerge from the termite host, indicating the need for further study. All nematode species were observed to develop to fourth-stage juveniles, pre-adult stages or adults with the exception of S. feltiae. Nematode concentration and incubation time had significant effects on the mortality of worker H. aureus. Different concentrations of nematodes have been tested for repellency effect on termites and the thresholds have been determined. Nematode infected termites were exposed to three different temperature settings for nematode development progress. S. riobrave consistently generated the highest infection levels and mortality of H. aureus in sand assays.