Predatory arthropods play a very important role in biological control. Besides prey, many of these predators are observed to visit flowers and to consume floral resources like nectar and pollen. Nectar and pollen can provide supplementary nutrients that either sustain predators until they locate nutritionally optimal prey or complement nutrients obtained from prey. Because of this, flowering plants are increasingly being established in intensively cultivated agricultural areas to support natural enemies. However, not all of the flowering plants have accessible nectar and pollen for predators, and the nutritional quality may differ. Especially the role of floral diet for predators is less studied. Adalia bipunctata L. (Coleoptera: Coccinellidae) is a generalist aphidophagous coccinellid and a common natural enemy in agroecosystem. Coccinellid species have been observed to consume nectar and pollen, but the effect of these floral resources for A. bipunctata is poorly known.The overall objective of this thesis is to explain and understand the value of floral resources as an alternative diet for predators (Manuscript I), with focus on A. bipunctata. We investigated the effect of floral resources on A. bipunctata larval development compared to prey diets (Manuscript II and Manuscript III), adult longevity and fecundity (Manuscript II), and finally how floral diet affect predation (Manuscript IV). Manuscript I presents a meta-analysis that investigated the effect of floral resources on predator longevity. We summarized published studies on the effect of floral resources (flowers, pollen and sugar solution) on predators. The results show that floral resources significantly increase predator longevity, especially sugar solution, followed by flowers and pollen. The effect of flowers vary greatly among plant species, those with open or exposed nectar are more likely to prolong predator longevity. Female predators survived longer on a flowers diet than males did, but no difference was found between females and males reared on sugar solution and pollen diets.Under laboratory conditions, the effect of different floral resources on A. bipunctata larval development were assessed (Manuscript II). The floral resources were: 1) five flower diets: Matricaria chamomilla, Daucus carota, Fagopyrum esculentum, Anethum graveolens and Sinapis alba; 2) four pollen diets from three plant species: Typha angustifolia, Malus pumila (two varieties) and A. graveolens; and 3) 1 M solutions ofthree sugars: glucose, fructose and sucrose. While larvae fed Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs as positive control treatment developed normally, larvae did not develop beyond the first instar on any of the floral diets. None of the four pollen diets differed significantly from the negative control where only water provided, but larvae lived more than two times longer on F. esculentum flowers and on sugar diets. In the study of the effect of different floral resources on A. bipunctata adult longevity and fecundity (Manuscript II), we found that sugar solutions, A. graveolens and F. esculentum flowers considerably prolonged A. bipunctata adult longevity, but pollen diets did not. Adults fed on sugar solutions had higher lipid content than those fed on pollen diets. Floral diets significantly prolonged adult longevity but floral resources alone did not support reproduction. The effect of F. esculentum flowers, the best performing floral diet, was further assessed on A. bipunctata larval development in combination with either limited or surplus aphid prey (rosy apple aphid, Dysaphis plantaginea (Pass) (Hemiptera; Aphididae)) (Manuscript III). When limited aphid prey was offered, F. esculentum flowers augmented A. bipunctata larval development, with (i) six times higher in survival rate, (ii) 25% shorter developmental time and (iii) 50% higher dry weight of newly emerged adults. Even on a surplus aphid diet A. bipunctata larvae with access to flowers developed faster, although no differences in the survival and adult dry weight were observed. This study demonstrated that the benefits of floral resources to A. bipunctata larval development manifests more clearly, when prey is limited. While floral diets increased longevity in A. bipunctata adults, such a diet also affected their predation rate on aphids (D. plantaginea) (Manuscript IV). Adults that had previously been fed sugar solution consumed less aphids during two hours compared to individuals that had previously been fed E. kuhniella Zeller eggs. No additional predator induced mortality was observed in aphids. In conclusion, A. bipunctata and other predators can benefit from floral resources, which can considerably increase their longevity. In particular, floral resource considerably prolonged A. bipunctata adult longevity and larval survival time, but floral alone did not support larval development and adult fecundity. On the negative side, a floral diet led to reduced adult predation. However, the increase in A. bipunctata adult survival could augment A. bipunctata abundance to compensate the decline in per capita predation. Many questions regarding the role of a floral diet for A. bipuctata and for predators remain to be investigated, and such knowledge can serve to improve the use of flowering plants in agriculture to improve pest management. The findings in this thesis highlight the importance of floral resource to many predators in conservation biological control.