Recent research at Ruakura has shown that the negative correlation betweenArgentine stem weevil (Lirtronotu bonariasis (Kuschel)) population survival (egg to adult) and egg density was density dependent. Density dependent mortalities could arise from pathogens, predators, parasitoids, larval combat and chemical releases by larvae andlor by the host plant. Large mortalities arising from pathogens, parasitoids, soil invertebrate predators and possibly Carabidae and Staphylinidae predators can be discounted in populations at Wairakei in the central North Island.Even without knowing the causative agent of the population mortality, any considerations for releases of natural enemies for biologcal control of stem weevil should act to augment this existing control. It is recommended that parasitoids be evaluated for release against late larval instar, pupae and adults.