Adult Blow Flies Host Diverse Carrion‐Associated Microbiomes

Blow flies (Diptera: Calliphoridae) perform important yet often overlooked roles in ecosystems as decomposers, pollinators and vectors of disease. Central to these functions are their associations with microbial communities, which are maintained through close contact with diverse microbe‐rich substrates such as carrion, dung and flowers. Despite these microbial relationships being pivotal to blow fly ecology, the blow fly microbiome remains poorly documented, particularly for wild populations. We used 16S/ITS metabarcoding to characterise the internal and external (i.e., whole body, including surface) bacterial and fungal communities of four blow fly species ( Calliphora stygia , Calliphora hilli , Lucilia sericata/cuprina and Chrysomya rufifacies ), analysing eight adult individuals per species from three sites in the Waikato region of New Zealand. Across species, bacterial community composition was broadly similar at the class level and dominated by Gammaproteobacteria , Bacteroidia and Bacilli , with C. stygia hosting the most diverse communities and Ch. rufifacies exhibiting a comparatively simple assemblage. Fungal communities showed strong overlap across species and were dominated by Dothideomycetes , the largest fungal class that includes many known plant pathogens. Despite subtle species‐specific signatures, most bacterial and fungal variation occurred among individuals within species, indicating that blow fly microbiomes lack strong host specificity and are shaped primarily by environmental exposure and stochastic colonisation processes. These results align with patterns observed in other mobile, generalist and saprophagous insects and highlight the ecological significance of individual‐level variation. Our study thus provides a valuable first insight into how microbial communities contribute to blow fly ecology and their diverse functional roles across landscapes.