Seasonal population trends of stable fly, Stomoxys calcitrans (L.), adults follow three general patterns around the world. Peak populations in the fall have been reported most commonly from Africa, Asia, Europe, Japan, North and South America. A single spring peak has been reported from Africa, Asia, Japan, and North America. The third most common population pattern is a large peak in the spring, usually during June, followed by a drop during the summer and a much smaller peak during the fall usually associated with fall rains in Africa and North America. In the great plains of Kansas, stable fly populations peaked during June and July. Damaging populations of stable fly adults were present for 6 wk during dry years and for 13 to 18 wk during wet years.