Parasites have co-evolved with their host for a long period of time, resulting in unique parasitic systems tailored to each host species. This makes them suitable for research on physiological function control through cross-species molecules like miRNA. The body louse, a vector of bacterial pathogens, is particularly valuable as a model insect due to their frequent feeding on human blood, which results in the continuous ingestion of human-derived miRNA and injection of salivary gland-derived miRNA into the human body. In this study, we conducted miRNA sequencing on body lice with mixed stages and identified 105 miRNAs, including 50 novel miRNAs. Sequence analysis of human miRNAs remaining in body lice and the functional analysis of these miRNAs are in progress.