Calf pens offer ideal breeding grounds for house and stable flies and are often target areas in fly-control plans. Sanitation is the cornerstone of a successful fly-control program, but keeping calf housing dry through frequent cleaning and bedding can be a difficult and labor-intensive task, especially in years with significant summer rainfall. Researchers from the University of California at Davis recently published the results of laboratory-scale studies investigating the use of sodium bisulfate to acidify bedding in calf housing (March 2010 Journal of Dairy Science). House fly eggs were added to dish pans containing rice hull bedding and calf manure. In one experiment sodium bisulfate was added at four different concentrations (zero, low, medium and high; equivalent concentrations would be 0.55, 1.10, and 1.65 pounds for a 32 square foot pen) three times per week for 23 days. In a second experiment, sodium bisulfate was added at low concentration three times a week, a single low concentration treatment 48 hours before the end of the experiment at eight days, or not added. Temperature and humidity levels were kept in a range that would support fly larvae development.

In the first experiment, sodium bisulfate reduced the pH of bedding and reduced the number of surviving fly larvae by 87, 99 and 100 percent in the low, medium and high concentration treatments compared to the control. In the second experiment, adding sodium bisulfate every three days reduced the number of surviving larvae by 90 percent and reduced the bacterial plate count by 68 percent compared to the other treatments. The researchers concluded that reducing bedding pH with sodium bisulfate created a hostile environment for bacteria. When this feed source was removed, immature flies died. Further studies using sodium bisulfate under the conditions of actual calf housing are needed to determine if this strategy will prove to be practically and economically viable.

Read the abstract.