The effects of dose-dependent envenomation by and parasitization of Pimpla turionellae Linnaeus (Hymenoptera: Ichneumonidae) on the ratio of hemolymph free amino acids of the host species Galleria mellonella Linnaeus (Lepidoptera: Pyralidae) pupae and larvae were investigated. Of the seventeen different free amino acids detected in the hemolymph of host pupae and larvae by high performance liquid chromatography, the ratio of free amino acids from parasitized and envenomated host pupae did not differ much when compared with those of unparasitized, null- or PBS-injected controls at different time points post-treatments. The exceptions to this trend were an increase in parasitized host pupae for glutamic acid with regard to other experimental groups at 4 and 8 h and a decrease in parasitized host pupae for leucine with regard to 0.01 and 0.05 VRE at 24 h post-treatments. In contrast to pupae, hemolypmh free amino acids of G. mellonella larvae differed upon venom injection among treatments and at different time points post-treatments. The ratios of alanine and leucine at 8 h and glutamic acid, serine, glycine+glutamine, valine, methionine, and phenylalanine at 24 h post-treatments differed from those of controls in treatment groups. However, there appeared no changes in the ratio of hemolypmh free amino acids in host larvae at 4 h post-treatments. Our study indicated that parasitism and experimental envenomation of G. mellonella by wasps resulted in different effects in the quantity of free amino acids depending on host developmental stage.