Live cells ofXenorhabdus nematophilusandX. luminescenswere inoculated subcutaneously into 9-day-old White Leghorn chicks and adult Swiss albino mice and intracerebrally into suckling mice. Infective-stage juveniles ofNeoaplectana carpocapsaeandHeterorhabditis bacteriophorawere inoculated subcutaneously into adult Swiss albino mice. No disease symptoms or mortality appeared in any of the experimental animals during the course of the experiment.