It is the time of year to remind cattlemen that the high levels of stable flies that will attack pastured cattle next spring and early summer most likely come from winter round bale feeding sites, says Alberto B. Broce, Kansas State University emeritus professor, livestock entomologist. "Over the last three decades we have seen a dramatic increase in the population levels of these bloodsucking flies."
When feeding on round bales, cattle waste up to 50% of the hay, which when mixed with cattle feces develops into an ideal habitat for the larvae of stable flies in the spring and early summer. The resulting populations of stable flies reach economically damaging levels during a period of about eight weeks (spring - summer) causing a loss of 0.5 lb. per head per day; the lower fly densities before and after this period also detrimentally affect cattle performance.
Broce recommends to help reduce the availability of larval media decrease the amount of wasted hay at the round bale feeding sites by:
- frequently moving the feeding tubs to prevent the accumulation of the hay-manure medium over one spot
- using modified feeders, such as the cone feeders, demonstrated to reduce the amount of wasted hay
- unrolling the round bales on pastures, but not over the same site
- spreading out the accumulated hay-manure medium to dry
Although stable flies are good fliers, capable of dispersing up to 155 miles, the population levels pestering a given herd are correlated to the number of flies emerging from round bale feeding sites in the vicinity. Therefore, implementation of cultural control methods can be a waste if neighbors do nothing to prevent the development of large populations of stable flies in their premises. "Working together to address the issue will be beneficial to all." says Broce.