Managing manure and conserving predators helps control flies in caged-layer poultry systems

Poultry manure supports the development of several serious fly pests (Axtell and Arends 1990). Fresh manure is rich in nutrients and is produced at the rate of one-quarter pound per hen per day, providing an ideal habitat for fly larvae to live and feed. The problem has become more acute in modern high-density poultry housing where manure often is concentrated in piles below the birds. The house fly (Musca domestica), most abundant in summer and fall, is the most important worldwide fly pest. Two smaller flies (Fannia canicularis and F. femoralis) are also common in poultry manure in California. The little house fly (F. canicularis) is an important spring and early summer pest. These flies generally do not impact production directly, although there is some potential for them to transport poultry pathogens among or within operations. Ongoing residential development on formerly agricultural or open lands near poultry farms has resulted in increasingly frequent land use conflicts between farms and their relatively new suburban neighbors. The main problem with flies is that the presence of too many can trigger nuisance complaints from neighbors and can violate local health ordinances. Egg farm managers can be compelled to implement expensive control strategies or even cease operations if unmitigated problems persist. M. domestica and F. canicularis were ranked number one and number two in a recent survey of pest importance in California poultry operations (Hinkle and Hickle 1999). Fly control options include chemical, cultural and biological techniques. Chemical fly control is still common and needed in some situations, with emphasis on the use of fly baits or selective insecticides that kill adult flies applied to surfaces that flies rest on. Overreliance on chemicals often leads to insecticide resistance, and direct application of most fly larvicides (orgaAs the rural-urban interface expands, controlling flies has become increasingly important on California poultry farms. Manure management is a critical component of keeping fly populations in check. Recent research demonstrates that the dry pad left behind after manure cleanouts in cagedlayer poultry systems aids manure drying because of the elevation and improved airflow. Most mites and beetles that prey on fly eggs and larvae are removed in a cleanout, although predator populations require longer than flies to recover. Leaving undisturbed manure (with a larger number of predators) adjacent to recently removed manure did not improve fly control significantly in open-sided layer houses, but might be more important in fully enclosed houses. Egg producers sometimes remove poultry manure in a pattern of alternating rows. However, the study indicates that such removal systems do not necessarily reduce fly populations.