Technical Abstract: The ancestors of cultivated sunflower, Helianthus annuus L., are native to North America and approximately 13 of the 51 species in the genus Helianthus are reported to occur in Canada. Sunflower was introduced to Spain in the early 1500s, gradually spread across the European continent, and was then reintroduced from Russia into North America by Mennonite immigrants to Canada beginning about 1875. Because sunflowers are native to North America, the phytophagous insect fauna coevolved with the plants for centuries. Sunflowers are utilized by a large array of insects as a source of food or shelter and serve as an excellent source of pollen and floral and extrafloral nectar and a source of prey for predators and parasitoids. Thus, the actual number of arthropod species that exploit sunflower is probably much larger. When sunflower was altered from its wild to a cultivated state, the sunflower community shifted from an interspecies mix to a monoculture, small patches to large hectarages, and low to high plant population densities. These changes have had an impact on insects associated with sunflower in its native home; the transition to the cultivated plant has been very successful for some arthropod species, which have become economic pests. In Canada, a number of insect species have successfully made the transition from native sunflowers to the cultivated crop and of these the following have caused some economic damage to the crop: the sunflower moth, Homoeosoma electellum (Hulst), the sunflower seed maggot, Neotephritis finalis (Loew), the banded sunflower moth, Cochylis hospes Walsingham, the sunflower beetle, Zygogramma exclamationis (Fabricius), painted lady, Vanessa cardui (L.), and the sunflower midge, Contarinia schulzi Gagne. This paper describes the biology of these and other phytophagous species associated with native and cultivated sunflowers, which occur in Canada and the Great Plains of the U.S. In addition, the natural enemies of a number of the key sunflower insect species are discussed.