Scientists Calculate Economic Impact of Biting Stable Flies on California Dairies

The Western IPM Center reported on research it funded on California dairies to calculate the economic impact of biting stable flies. The project found that stable flies are a serious seasonal problem for dairy producers that costs the average 2,000-milking-cow dairy at least $10,000 a year in lost milk production in addition to the cost of control measures. Cows that bunch to avoid the biting flies don’t rest, eat, or drink as much, and consequently don’t produce as much milk. Researchers also found that higher stable fly counts resulted in more bunching, and that stable flies and bunching were worse in pens near the perimeter of dairies and worse generally on dairies surrounded on three sides by field crops. In addition, fly counts were higher on dairies that incorporated agriculture by-products or wet distillers grain in their feed, while bunching was reduced on dairies that regularly cleaned manure away from fence lines and pen edges.