none Overwintering survival of the sunflower stem weevil (SSW), Cylindrocopturus adspersus (LeConte), varied with microhabitat of the larvae. Survival was significantly higher for larvae protected within the sunflower stalk compared with larvae exposed in the soil. Survival ranged from 11.9 to 68.4%, 9.2 to 58.6%, and 3.7 to 33.2% during the fall-winter seasons of 1981-1982, 1982-1983, and 1983-1984, respectively. Nealiolus curculionis (Fitch) and Tetrastichus ainsliei Gahan parasitized 10.6, 7.0, 29.8%, and 0.6, 1.2, 0.3% of the SSW larvae recovered from stalks collected in the fall in 1981-1982, 1982-1983, and 1983-1984, respectively. Microhabitats favoring SSW survival also favored parasitoid survival. Whole animal physiology; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Population dynamics; Abiotic factors; Physical factors; Land and freshwater zones; Nearctic region; North America; USA Cylindrocopturus adspersus (Curculionidae); Dormancy; Hymenopteran parasites; Nealiolus curculionis & Tetrastichus ainsliei; Host & parasite overwintering survival; Survival; Overwintering, influencing factors; Temperature; Overwintering survival relationship; North Dakota; South east; Overwintering survival, influencing factors & hymenopteran parasites Nealiolus curculionis (Braconidae ); Tetrastichus ainsliei (Eulophidae ); Dormancy; Coleopteran hosts; Cylindrocopturus adspersus; Host & parasite overwintering survival; Survival; Overwintering; Temperature; Overwintering survival relationship; North Dakota; South east; Overwintering survival, influencing factors, coleopteran host