Laboratory studies were conducted to determine the effects of host density on development time, egg dispersion, fecundity, sex ratio, longevity, and glycogen, total sugar and lipid levels of Bracon hebetor Say, 1836 (Hymenoptera: Braconidae), parasitizing Ephestia kuehniella Zeller 1879 (Lepidoptera: Pyralidae) at 26 +/- 2 degrees C, 60 +/- 5 % RH and continuously illuminated conditions. One pair of the parasitoids (age<24 h) were exposed to one, two, four, and eight hosts over a 24-h period during ten days. Host density had no significant effect on development time of B. hebetor. For both sexes, it lasted almost 14-15 days at all host densities. Longevity of females did not vary significantly with host density, whereas males had some variations. Females appeared to allocate eggs in relation to host density. However, total number of eggs laid per female was similar at all host densities. When female had only one host larva, progeny emergence was lowest compared with other host densities but percentage of male progeny did not change with host density. We also compared the glycogen, sugar and lipid reserves of recently emerged unfed female and male B. hebetor maintained different host densities. Host density had no significant effect on glycogen levels of female and male wasp, whereas sugar and lipid levels showed some variations in both sexes.