We assessed the life history parameters and temperature requirement of a Korean population of the endoparasitoid Aphelinus asychis Walker (Hymenoptera: Aphelinidae), using Aphis gossypii Glover (Hemiptera: Aphididae) as a host. We first measured the time from egg to mummification (i.e., pupation) and mummification to adult emergence (i.e., pupal period) at 25°C. The pupal period was significantly longer than the egg to pupation period in both genders, unlike in other regional populations of the species. Females produced an average of 342.9 mummies, he highest reported fecundity among the various regional populations of this species. Age-specific realized fecundity peaked between the 4th and 7th day (23.3–24.8 mummies a day). The intrinsic rate of increase (r_m) was 0.255 offspring per female per day. The parasitoids were then reared at eight constant temperatures between 15 and 32.5°C. The developmental time from egg to adult emergence decreased from 27.8 to 9.8 d. The lower developmental thresholds (T₀), estimated by linear regression, for the egg to mummy, mummy to adult, and egg to adult stages were 6.7, 6.8 and 6.7, respectively. The thermal constants for each of the three periods were 115, 126, and 243 DD. We compared these parameters with published data of A. asychis from other regions reared on different hosts and representative species of aphid parasitoids in Aphidiinae (Braconidae) reared on hosts including A. gossypii. The T₀'s of A. asychis were higher than those of Aphidius colemani and Aphidius matricariae when using A. gossypii.