Background: The main hematophagous flies acting as mechanical vectors of pathogens in mammals are tabanids, stomoxyine flies and some hematophagous Musca spp. Species-identification using dichotomous keys is based on external morphology of the flies. Their proper use requires specific skills and confirmation by shipment of specimens to specific taxonomic area specialists. Although potentially very high (especially in tabanids: 4400 species), the species-diversity of biting flies in livestock is generally limited in a given area (on average 5–10 species). A quick and user-friendly identification would be useful to veterinary technicians to fill gaps in their knowledge and support any control program. Method: Based on the facilities brought by numeric photography and the most frequent criteria used in the dichotomous entomologic keys, we generated guidelines to easily create a complete illustration of hematophagous flies external morphology, including dorsal, ventral and lateral views of whole body, head, antenna, thorax, wings, abdomen, legs and some other details, when necessary. Results: Application was made through a series of 32 pictures allowing user-friendly description and identification of the female Tabanus rubidus, a common mechanical vector of pathogens in Asia. Conclusion: These guidelines will help generating illustrated descriptions of hematophagous flies, which will ease their identification, even at distance. Further on, genotyping of the insects might be a nice complement. Once adopted, these guidelines might be a basis for a better knowledge of the identity, biology and ecology of the hematophagous flies encountered in livestock, and thus, for the development of adapted control measures.