Buffalo flies do not have a special overwintering phase and only survive winter by finding favourable, moist sheltered areas where they are protected from frost. When conditions become suitable again in summer, the buffalo flies build up in numbers and spread out from these foci. In many areas of Australia, particularly in locations away from the coast where winter is cold and dry, the flies die out during winter and then reinfest each year (Figure 1). Newly emerged buffalo flies can fly up to 10 km to find cattle. However, in practice if cattle are close, most flies do not disperse far. Movement of infested cattle, particularly as cattle relocate to summer pastures can be an important means of spread. Checking purchased or introduced cattle for flies, and treating if necessary, before introduction of these cattle to winter fly free areas, can help slow the summer build-up of flies.
Figure 1. Distribution of buffalo flies in Australia. Image courtesy of Meat and Livestock Australia.