Buffalo flies, Haematobia irritans exigua, are similar to horn flies in size and appearance and in feeding and breeding habits. The buffalo fly is a primary pest of cattle and water buffalo but occasionally feeds on horses, sheep, or wildlife.
Buffalo flies spend most of their time resting or feeding on cattle. ... They are found most commonly on the head and back of cattle although during hot parts of the day, they are often in highest numbers on the belly and lower flanks. They also infest buffalos and sometimes bite and irritate horses, dogs or even humans.
Various chemical groups are registered for use to control buffalo flies in NSW. They include synthetic pyrethroids (SP), organophosphates (OP) and macrocyclic lactones (ML). These chemicals are available in a variety of application methods, including spray, pour-on, and insecticidal ear tag.
Google gave me this info , perhaps catch one or two and see if they match a photo of buffalo flies