Parasitoid wasps play a crucial role in the efficient control of pests, a substantial menace to human health and well-being. (Ratzeburg) stands out as the most effective egg parasitoid wasp for controlling American cockroaches, but accurate and stable reference genes for quantitative real-time polymerase chain reaction of genes are still lacking. In this study, we assessed seven candidate nuclear genes, including (), (), (), (), (), (), and () of . By analyzing expression stability with four algorithms (Delta Ct, geNorm, NormFinder, and BestKeeper), as well as comprehensive ranking with RefFinder, we identified as the most stable reference gene for the larval, pupal, female adult, and male adult stages. Subsequently, we estimated the transcript levels of vitellogenin () and cuticle protein () after normalization with across various developmental stages. Significantly higher expression levels of and were observed in pupae and female adults, respectively, consistent with previous findings in other insects. This study offers a reliable reference gene for normalizing transcription levels of genes.