During a survey for pathogens of black beetle, high mortality was observed in a population in kikuyu pasture at Wharepapa, near Helensville. Several pathogens were isolated from larvae and adults, including a protozoan (possibly Adelina sp.), a rickettsia, a fungus (Beauvaria sp.), a neoaplectanid nematode, and a small RNA virus. The virus was transmitted to larvae of Pseudaletia separata, Galleria mellonella, Aphodius tasmaniae, and Pericoptus truncatus, and a fatal paralysis ensued after 14–37 days. The potential of the neoaplectanid nematode and the virus in control is discussed.