The pteromalid Conomerium sp. is ono of the gregarious endopar­as:toff:Is attacking the pink stalk borer, Sesamla attics pupa in Egypt. The biological and morphological studies were not adequately investigat­ed before. Accordingly, this work was conducted to study this aspect for the sake of easy differentiation between this species and other species belong to genius Conornorium. The different immature stages of Conon­orium sp. (egg, four larval !listen. propane and pupa) were briefly de­scribed. The mean incubation period is 1.75* 0.25 days. the moan total durations of the larval stage (4 Meters) are 2.25 3 0.25. 3.5 t 0.09, 3.75 2 0.20 and 4 i 0.18 days, respectively. Whereas the prepupal and pupal stages lasted 1.13 ± 0.12 and 8.5 ± 0.23 days. respectively at 25 V and 85 ± 5 R.H. The two sexes of the parasitold were dill egentiated and described. Mating and oviposilion processes are described Pupae of 8 lepidopterous species were tested as hosts for Conomotium sp. Two species. S. cretke and Agrotis ipson were attacked by the parasitoid fe­male. Effects of different types of supplementary food on the longevity of adults wore tested. The suitable temperature for rearing the palest. told is 25 °C. where the female lived for a mean period of 27 days and produced an average of 189.3 ± 32.48 adult parasitoids during its life span with sex ratio of 1 male : 10.47 female. It was found that mating did not affect the ovipositional activities, life-span. Oviposition partheno­genesis occurs and unfertilized eggs give rise to males only. The number of generations of paresitoid per year in laboratory were 13 generations. Adults (females and males) of the pteromalld Conornorium sp. were stored at 10 *C for different periods of storage. Mortality rates were low­er among females than males. Also. cold storage of males for longer peri­ods more than 25 days caused detrimental effect on the fertility of males. The cold storage for 35 days led to a sox-ratio of 1 male: 0.2 fe­male when storage males copulated with freshly emerged females. It was found that 90 days period of storage may be considered the maximum favorable period of storage for virgin or mated females without any det­rimental effects on their own or their progeny, fecundity or longevity. Storage studios are Important to Obtain the greatest numbers of parasit­ic adults at any required time much early before occurrence of economic damage of the target insect pest S erotica.