July 7, 2004 | By: Aimee Heald-Nielson

Most of Kentucky has seen frequent rainfall over the past few months, creating a breeding haven for flies. Flies often plague livestock operations.

“The longer breeding sites stay moist, the more flies they can produce,” said Lee Townsend, entomologist for the University of Kentucky College of Agriculture. “House flies and stable flies breed in wet mixtures of manure and spilled feed around confinement areas or forage racks, while face flies and horn flies use fresh deposits of cow manure in pastures.”

Usually by mid-summer there is less humidity and air movement and more sunlight which helps dry sites and makes them less suitable for breeding. Townsend said, however, our steady parade of rains can play havoc with even the best manure management and fly control plans.

“Sanitation and manure management around confinement areas is the key to breaking fly life cycles,” he said. “In the long run, no reasonable amount of insecticide can overcome the breeding potential of optimum sites.”

Townsend offered some tips to help combat fly problems. He said to check for low spots around feeding and loafing areas where pooled water and urine can keep feed, bedding, and manure wet and try to fill them or create a ditch so water can move away quickly after a rain. 

“It’s also important to inspect watering devices frequently for sticking floats or leaks and grade around these spots so that water will be directed away,” he continued. “Keep areas next to feed bins and feeding aprons as clear of waste accumulations as possible. Two or three scoop shovels of organic matter can produce several hundred flies very quickly.”

He said if manure is stored for later disposal, producers should keep it stacked and packed and maintain steep side slopes so that water drains off as much as possible. Keep manure lagoons agitated so no crust is allowed to form - these crusts become fly breeding areas. Use screens and sticky fly traps around entrances to keep flies out of milk rooms and swine buildings. Check self-application devices like back-rubbers and dust bags frequently. Wet dust will clump in bags and not get dispersed on the animals, and spent oilers need to be recharged.

Although not a satisfactory long-term solution, insecticides can be important tools to temporarily reduce or knock back fly problems until sanitation problems can be addressed.

“Residual sprays can be applied to places where flies rest,” Townsend said. “These surfaces can be identified by the accumulation of fly specks. Spray them to runoff but be careful to protect feed and water from contamination. Wettable powder (WP) formulations may provide longer residues on surfaces than emulsifiable concentrate (EC) formulations.”

Foggers or space sprays with quick knockdown insecticides (pyrethrins) can kill large numbers of flies but these have to be applied at regular intervals (usually 2 to 3 days). 

In some situations, fly baits can be scattered to kill adults. Baits are likely to be more effective if there are not many competing food sites to attract flies. 

“There are some larvicides/insecticides that can be applied directly to breeding sites to kill maggots,” Townsend said. “Generally, insecticides will break-down fairly rapidly in manure but direct contact with larvae can help to reduce fly production.”

For more information, check the 2004 Insect Management Recommendations for the appropriate livestock species to see what products are registered for use or check with your local county Extension office.


Writer: Aimee D. Heald 859-257-4736, ext. 267

Source: Lee Townsend 859-257-7455