By Marc Lalonde Biosecurity Technician Vétoquinol Canada
Flies are a nuisance to every farmer, but can be controlled if the proper steps are taken
By Marc Lalonde Biosecurity Technician Vétoquinol Canada
Flies are everywhere and can cause increased stress to both animals and workers. As urban development rapidly stretches into agricultural areas, the demand for effective fly control has become a large concern, especially in large numbers, where flies can cause considerable annoyance to the farmer and surrounding neighbours. Poultry barns are the perfect breeding ground for flies, since they offer perfect conditions like heat, moisture and plenty of organic material. Fly control should be a regular and important part of managing any poultry farm.
The housefly develops in multiple stages: egg, larva, pupa and adult. Female flies will lay their eggs over three or four days in batches of about 150 eggs on various types of moist, decaying organic materials. Manure can contain as many as 3,500 eggs per kilogram!
The larvae, known as maggots, are white and will grow in the manure until they are ready to transform into an adult via the intermediate stage – the pupa. This stage in the fly’s growth cycle occurs in dry areas and the pupae are brown-red in color. In the barn, visible adult flies represent only 15 per cent of the population, whereas eggs, larvae and pupae that are hidden in the manure account for the other 85 per cent.
Like most insects, flies are capable of surviving winter inside barns that offer moderate climate conditions. Under ideal conditions, the life cycle of a fly can be as short as seven to 10 days when heat and moisture are high. Flies are active from the beginning of spring, will be present until winter arrives and are capable of traveling for many kilometres, but will usually stay within one kilometre of their breeding sites.
Integrated pest management
IPM consists of controlling pests at an acceptable level, because eradication of flies is almost impossible due to the nature of poultry operations. There are four steps in integrated pest management: prevention, surveillance, intervention and evaluation.
Integrated pest management means having a good knowledge of the pest that is infesting the barn. Identifying what pest is infecting your barn, in addition to their favourable conditions and behaviours are important first steps because different flies can have different biologies.
Installing a means of detection on the farm to evaluate the fly population will help to determine the threshold needed for intervention. Monitor flies with sticky sheets or spot cards, which are white 3‘’ x 5’’ cards, typically placed in fly resting areas. Install a minimum of five cards and count vomit or fecal spot on the cards weekly in a log-book to record results. A count of 100 or more spots per card indicates a need for intervention.
Apply, when needed, a combination of different means of physical, chemical, biological, and mechanical interventions to best control or eliminate fly populations.
Almost 85 per cent of the fly population in a barn is in the manure and bedding, and thus it is necessary to act not only on the adult flies, but also on the developing juveniles through management of the litter and manure. Flies reproduce in wet manure, feed and bedding, so wet areas in the barn must be limited wherever possible. With a life cycle as short as seven to 10 days, twice weekly removal of wet organic material will help to break the life cycle.
Stockpiling of manure near the barn is not recommended, as it may attract more adult flies, so the removal of manure from the proximity of the barn is the best solution. Composting the manure can also kill developing juveniles, but the pile must be tarped to allow the temperature to rise to 50 C (120 F), and for better composting results, the manure pile should be turned every three to four days
As for the bedding, coarse sawdust is a better moisture absorbent than straw. It will create dryer litter and therefore fewer opportunities for flies to lay their eggs. When straw is used, the moisture level is higher; giving flies a better environment to reproduce in.
Flies reproduce in damp areas in the litter, especially under water lines, so proper maintenance is key to avid leaks.
Ventilation is another factor that can help in the process of controlling flies through adequate air circulation that keeps the litter dry.
Another physical control method is to install fine window mesh on the air intakes in order to prevent flies from infiltrating the barn. Additionally, removal and disposal of dead birds and broken eggs on a daily basis will help to reduce fly reproduction. Around the barn keep grass short – this will remove resting areas that are cooler for the flies and it will also maintain good airflow in the barn to help dry the litter.
Insecticides are products that are used to help in the control of insects. There are many insecticides on the market and by nature these products are hazardous – therefore, precaution is needed at all times. Follow label instructions for proper use of products. Appropriate protective gear should always be worn when handling and applying these products.
In cases of heavy infestation of the barn at the end of a production cycle, fogging can be used to eliminate adult fly populations. This is critical because flies reproduce quickly, so it should be started immediately after birds are loaded. Flies will hide during barn cleanout and re-infest the barn when conditions allow. Be sure to close all doors, stop ventilation and fog the barn with a fast acting pyrethrin-based insecticide to eliminate adult flies. Finally, be sure to leave for two hours and ventilate the barn before re-entry.
A residual insecticide should be applied inside the barn when the cleanout is finished to ensure a residual activity for several weeks by applying the insecticide until run-off on walls, posts and ceilings. A common practice is to mix the insecticide with a disinfectant, but this should not be done unless both labels permit this concurrent use. The chemical reaction between insecticide and disinfectant may result in a solution that is unsafe, or with one or both ingredients being neutralized. For best results, applications should be done separately; start with disinfection and finish with insecticide.
Fogging a residual insecticide is not as effective as spraying directly on walls because there is often not enough solution in the fogger to ensure maximal surface coverage, and this can promote the development of fly resistance to insecticides. Insecticide active ingredient rotation is also necessary to prevent resistance from occurring.
Another option during barn cleanout is to apply a residual insecticide on the outside walls of the barn as well. Apply insecticide only when the label allows for exterior application in accordance to municipal regulations. This application will offer additional treated surfaces for flies to come in contact with. However, this application should not be done while birds are in the barn because the mist will be taken in by the ventilation system.
Granular bait contains an insecticide, an attractant (usually sugar) and sometimes a synthetic pheromone. Some baits are coloured blue, because it is the color flies can see best. Be sure to spread out fly bait stations within the barn and apply the stations at a rate of 250g/ 100m2. The stations should also be put out at the beginning of the fly season and renewed once a week throughout warm weather near where flies congregate such as resting areas, windows and lights. Fly bait stations are available from manufacturers, but it is also possible to build stations with fine window mesh or plastic jugs. When setting up fly bait stations, take caution not to contaminate feed and water when doing so.
The use of biological control agents in fly management programs is an alternative to chemicals, with different parasitic insects available on the market. Please refer to distributors and users for information.
Capturing and preventing the infiltration of houseflies in barns is another means of control. There are different formats of sticky sheets and cords that can be used in the barn and when placed in the right areas and in appropriate quantities, these traps will reduce the population, especially when placed in the spring. It is possible to enhance the attractiveness of traps by adding an attractant such as sugar, molasses or fly pheromones. Installing a fine mesh on air intakes will also prevent the infiltration of flies into barns.
Lastly, evaluate the efficiency of your chosen interventions (efficacy, quality, quantity, cost, labor, etc.) in order to recall the events and to be able to analyse them. Keep records of your interventions in a dedicated logbook and make adjustments as needed.
A control program is successful if flies are kept at, or below, acceptable levels. It is difficult to determine just what factors have the greatest effect on flies, but combining different means of control will often be necessary. An early start in spring will give better results when summer heat and moisture arise.
You can also request the services of a Vétoquinol Biosecurity Technician to schedule a farm visit and help educate your staff and yourself on flies and how to control them. The technician can set up a specific biosecurity program for your property that is effective and simple to follow, as well as be a great resource to help you tackle the unique problems on your barn as they arise.