Trichogramma species are the most widely used biological control agents against lepidopteran pests. They prefer sugar-based substances as foods, especially plant nectar. Flowering plants have been shown to differ with regard to their attractiveness to parasitoids and nectar accessibility. The value of floral nectar and laboratory diets as food sources for Trichogramma euproctidis (Girault) (Hymenoptera: Trichogrammatidae) was assessed in the laboratory by testing the effects of different floral nectars (dandelion, dog-fennel, dead nettle, willow, plum) and artificial diets (honey, grape molasses, raisins, beet molasses, glucose and sucrose syrups, and egg yolk) on the longevity, capacity for parasitism and adult emergence. Trichogramma euproctidis females that fed on honey 10.5 days) and dandelion flowers (8.7 days) lived significantly longer than females that fed on other floral nectars and artificial diets. The females fed on raisins (2.9 days) and water alone (2.6 days) had the shortest longevity. Trichogramma euproctidis females that fed on sucrose syrups (30.9 eggs), honey+egg yolk+water (29.13 eggs) and honey (28.0 eggs) parasitized significantly more hosts than females that fed on other floral nectars and artificial diets. The females fed on raisins (18.5 eggs) and plum flowers (15.5 eggs) were shown to have the least parasitizing ability. The results indicate that carbohydrates such as dog-fennel nectar or honey can increase the performance of the wasp parasite. Although floral nectar qualities may be of greater importance to parasitoid longevity when selecting floral resources for conservation biological control, the artificial diets proved to be suitable foods for sustaining the development and reproduction of T. euproctidis.