Hybrid sunflower florets have been reported to contain two acetone soluble kauranoid compounds that conferred resistance, in the form of "larvicidal" effects, to the sunflower moth, Homeosoma erecteilum (Hulst). The objective of this study was to determine if the seed, florets, ray flowers or leaves from a hybrid sunflower contained acetone soluble kauranoid or other components that conferred resistance to larvae of the banded sunflower moth Cochylis hospes Walsingham. The mortality and development time of larvae reared on diets prepared with unexlracted seed (rearing diet), floret, ray flower or leaf material were compared with mortality and development of larvae fed complementary diets that contained acetone extracted seeà, floret, ray flower or leaf material as the test ingredient. Important findings of the study were as follows: l ) larval mortâIity decreased significanily when larvae were fêd diet prepared with ace tone-extracted seed compared with diet with unexrracted seed 2) substitution of florets into the diet was not Iarvicidal although substitution of florets into the diet resulted in a significant increase in rarval-development time, 3) the devel opment time on diet with ray flowers significanfly increased, 4) mortarity on the leafdietwas as high as on the rearing diet, and b) the effects offloretsl ray flowers, or leaves on mortality or development time of c. hospes were not related to acetone soluble components in sunflower because the resurts in each case were similar when either acetone extracted or intact floret, ray flower or Ieaf material were substituted in the diet. The difference in responce reported here for C. hospes and those reported for the sunflower moth H. eteitertum may reflect species differences in adaptation to the host plant or there may be significant differences in the chemical composition of different sunflower hybrids. Selection of sunflower for constituents that conferred resistance in the form of increased mortality and development time of C. hospes could be useful for greater control of this pest insect.