Mortality of pre-adultRhinocyllus conicusFroelich on musk thistle (Carduus nutansL.) at Pulaski, Va., in 1972 was 68.0%. The range in mortality at 11 sampling sites was 56.6–95.8%; greater losses occurred in open, unsheltered pasture. Egg and early instar larval mortality (58.3%) resulted primarily from egg destruction by wind and rain. Mortality of late instar larvae and pupae (9.7%) was partially attributable to parasitism (3.6%) byAliolus curculionis(Fitch),Bracon mellitor(Say), andCampoplex polychrosidisViereck. Some loss of larvae and pupae was caused by crowding.