Flies continue to be a nuisance in egg production operations, especially in large in-line high-rise complexes. This production system allows the propagation of flies especially when complicated by deficiencies in the design of housing, management of ventilation or removal of manure.

Flies are adapted to reproduce at a prodigious rate. Each female fly can lay up to 500 eggs over a 15 to 25 day life cycle. Given wet manure, warm temperatures and humid conditions prevailing in spring and early summer, fly breeding may result in population explosions which overwhelm conventional control measures including application of insecticides and feed-through larvacides.

With the development of resistance to synthetic pyrethroids and organophosphates and also larvacides such as cyromazine, alternative methods of control are necessary. During the past few years many producers are reevaluating integrated pest management coupled with Biologically Integrated Insect Management to control flies.

Problems contributing to fly control 

Typical A-frame cages over deep pits allow fly breeding on deflector panels and crossbeams in addition to the rows of manure.

Annual clean out of pits during spring months results in removal of beneficial insects which serve to suppress breeding of flies. In the absence of “beneficials”, flies will breed without natural control through predation.

Many high-rise houses have inadequate ventilation capacity especially when exhaust fans are throttled back during cold weather.  Manure serves as a “water-sink” retaining moisture from respiration, defecation and urination by the flock, water from leaking nipples, seepage from the exterior and condensation from inadequately insulated roof structures.

In an attempt to reduce capital and operating costs many operations have inadequate pit ventilation from turbulence fans which are necessary to dry the crust especially at the apex of manure rows.

A program of complete removal of manure from all houses on a complex will promote fly breeding especially if followed by placement of young flock since pullets normally excrete wet droppings through to peak production. Under prolonged high temperature water intake may rise above 5.5 gallons per 100 hens per day which results in both wet droppings and increased respiratory release of water.

Integrated pest management

An integrated pest management program involves effective management of the water content of manure by effective ventilation, the use of beneficial insects and the judicious application of insecticides.

Management procedures to reduce fly breeding in high-rise houses include:

  • Maintaining effective ventilation rates and operation of turbulence fans in pits.
  • Composting manure rows under the cages.
  • Periodic removal of manure from houses on a rotational basis with composting to produce a value added product or disposal by spreading in a remote location.
  • Removal of manure from houses during winter which is possible using a composting installation.
  • Alleviating water leaks and seepage of water in to the pits due to defective drainage.

Many of the problems experienced in high-rise houses are obviated with on-belt drying installations coupled with weekly removal of manure from houses for composting or disposal.

Biological integrated insect management

A range of beneficial insects are available commercially which attack the premature stages of the lifecycle of flies. Generally all these beneficials with the exception of Ophyra prorogate and function in manure with a moisture content below 50%. Accordingly, control using beneficials is largely dependent on appropriate management of the water content of manure. Most of the beneficials have slower reproduction cycles than flies. When introducing a new population of predators there is a lag period during which fly breeding advances at a rapid rate overwhelming the capacity of beneficials. Frequently individual programs must be developed for specific farms to take into account the design of housing and equipment, placement of flocks, management systems, manure removal programs and resistance to insecticides.

It is axiomatic that organophosphate insecticides will destroy beneficials although the use of cyromazine if effective can be used with beneficials with the exception of Ophyra.

Each supplier of beneficial insects can tailor a program involving their species of insect with respect to frequency of application and numbers of adults or immature stages supplied. 

The following companies supply beneficials:

IPM Laboratories  - Ophyra (Hydrotaea aenescens); Parasitoid wasps (Spalangia cameroni/S. Nigroema. Mucidifurax raptor and  M. raptorellus); and Hister Beetles (Carcinops pumilio)

IPM Laboratories also markets Hister House traps to gather Carcinops beetles prior to clean out so that they can be used to repopulate the manure base remaining in the house after the bulk of manure has been removed. For further information refer to the company website www.ipmlabs.com.

Kunafin Insectary  - This company supplies parasitoid wasps to prorogate a beneficial population in manure remaining in houses after clean-up. Kunafin also supplies pheromone baits and traps. The company offers extensive technical support to develop specific control programs. Additional information is available on the company website www.kunafin.com.

Fungal-based products

JABB of the Carolinas have developed an entomopathogenic fungus (Beauveria bassiana) which kills both adult flies and larva. Marketed as balEnce biopesticide by Terregena, the compound can be sprayed on defector panels and manure rows. Both larva and emerging adults are infected with the fungus which results in death within days. It targets only adult flies and larvae and does not affect beneficial beetles or parasitoid wasps. baLence is also available as a solid bait to be placed in suspended stations.  Terregena also supplies parasitoid wasps and Hister beetles. For further information access jim@jskinner.com

An array of insecticides

Organophosphate insecticides with residual activity can be sprayed on walls and passageways above the level of the pit.  This should not affect beneficial insects and will destroy adults, reducing the rate of reproduction.  Organophosphates should be used sparingly and only if fly populations undergo rapid increase.  This is generally evidenced by the number of flies on the walls and ceilings.  Fly populations can be monitored quantitatively using a sticky fly strip applying a standard procedure. An operator walks the same aisles or periphery of the house, recording the number of flies adhering to the strip.  Fly speck cards can be used although results are extremely inconsistent.

Fly baits can be placed in suspended containers or coated onto cards placed on the walls and support beams in the pit area above manure piles.

Synthetic pyrethroids can be used to suppress adult flies.  Generally these products have limited residual action and require frequent application but should be carried out on walls in the work areas and ceilings avoiding drift into the pits.

When using any insecticide, statutory label instructions should be strictly followed and care should be taken not to contaminate eggs or too expose unprotected workers in the house. Resistance of flies to insecticides should be constantly monitored. Using compounds to which flies are resistant is ineffective and costly.

The bottom line

Conventional insecticide-only programs which frequently are of limited effectiveness may cost as much as $50,000 annually for a 1-million bird complex. Integrated pest control programs have a relatively high initial cost of up to $15,000 to $20,000 but thereafter with effective ventilation and manure management costs are minimal. Most fly problems are effectively self-inflicted due to improper management of manure and ventilation. On-belt manure drying installations are generally not affected by flies due to drying by effective ventilation and frequent removal to a composter.  Flies are unable to complete their lifecycle in dry manure especially when present for less than 5 days.

Control of flies improves the quality of the environment for the flocks and workers and alleviates complaints from neighbors resulting inevitably in the involvement of regulatory agencies. High fly populations may contribute to tapeworm infestation of flocks and may disseminate viral and bacterial infections including pathogenic E. coli. Flies can be controlled by efficient, diligent and continual application of integrated pest management systems.