The adult females of many parasitic Hymenoptera feed on their host insects to gain nutrients for egg production, a behavior known as host-feeding. Host-feeding is an essential component determining female fecundity for a number of parasitoid species. The size of adult females is widely recognized as a factor that intimately affects their fitness, including fecundity. Association between host-feeding and female size would then be expected but this has received poor attention so far. Here we studied the relationship between female size and host-feeding behavior, using Itoplectis naranyae, an ichneumonid endoparasitoid of many lepidopteran pests in rice paddies. During the early stage of female life, larger females fed on a greater number of hosts whereas the number of hosts oviposited did not differ among females of different size. In addition, larger females took larger host meal from single host individuals. Female size did not affect when females fed on a host for the first time. There was no significant relationship between the day of the first host-feeding and the number of hosts oviposited until that day. The age of females did not affect the size of host meal. We discussed the relationship among female size, fecundity and host-feeding and how female size affected egg production in the later stage of female life. Galleria mellonella (Pyralidae) : Host Itoplectis naranyae (Ichneumonidae) : Parasite Biometrics; Nutrition; Reproduction; Reproductive productivity; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts Galleria mellonella; Hymenopteran parasites; Female parasitoid feeding on host; fecundity & female size relationships; Itoplectis naranyae Itoplectis naranyae; Size; Female body size; Feeding behaviour; Fecundity; Lepidopteran hosts; Female adult feeding on host; fecundity & female size relationships; Galleria mellonella none