Abstract: Parasitoid adults can directly feed on floral nectar and honeydew containing monosaccharides and disaccharides. The effects of sugars, glucose, fructose, maltose and mannose on longevity, fecundity and nutrient reserves of Meteorus pulchricornis (Wesmael), a larval endoparasitoid of the beet armyworm, Spodoptera exigua (Hübner), were assessed in this study. Results showed that longevity of M. pulchricornis fed with the above four kinds of sugars was 25.9, 21.3, 21.5 and 11.1 d, respectively, which were significantly longer than that of the water control. Mean number of offspring was 72.8, 51.1, 55.8 and 8.6, respectively; while the mean number of offspring fed with water was only 4.3. When fed with the above sugars, M. pulchricornis could accumulate total sugar to a great degree, and lipid content in the insects fed with glucose, fructose and maltose increased significantly as compared with that in the water control. However, a significant decrease of lipid content was observed in the insects fed with mannose. In addition, protein content in M. pulchricornis fed with the above four sugars reached to the highest level during the early days of oviposition peak period, and decreased to the lowest level right before wasp death, the two levels were significantly different.