none Three species of Hymenoptera were reared from overwintering larvae of a sunflower stem weevil. Cylindrocopturus adspersus (LeConte), collected in North Dakota, South Dakota, and Minnesota in 1979 and 1980. These included: Nealiolus curculionis (Fitch) (Braconidae); Tetrastichus ainsliei Gahan (Eulophidae); and Mesopolobus sp. (Pteromalidae). N. curculionis was the most prevalent, representing about 90% of the total number of parasitoids. All three species are endoparasitoids, overwintering within the host weevil larva. N. curculionis and Mesopolobus sp. are solitary parasitoids, and T. ainsliei is a gregarious parasitoid, yielding up to 13 adults per host.