Keeping poultry is an enjoyable and rewarding activity for many people, but as the weather warms up, the henhouse can become a magnet for flies. Why are flies attracted to our poultry sheds, why does it matter, and what can we do about it if we prefer not to use insecticides?
Why are flies attracted to poultry?
Flies are attracted to poultry sheds for two main reasons. Firstly, for many species of fly, the young adult female needs to feed on protein before they can mature their eggs, and poultry manure offers that good source of protein. Secondly, the manure itself is an ideal place to lay eggs as it is a great food source for the hatching fly larvae.
Flies are quite inactive during the cool winter months and reproduction ceases in the cold. The adult flies live for longer in cool conditions and may persist in sheltered crevices of chicken coops for several months, coming out occasionally on a sunny day to forage briefly before hiding away again. But more importantly, larvae that fed in manure beds in autumn will have buried their way down into the soil, away from any extremes of cold, and will subsist there until temperatures begin to rise again.
In early spring, flies emerge from their puparia in the ground in large numbers and start life as immature adults. At this stage, females are driven to forage for the required protein in their diet in order to supply their eggs with nutritious yolk. Males may also be attracted to accumulations of manure because they become a great place to pick up a mate. Once the females have fed on enough protein, they can develop a batch of mature eggs to become gravid. Their focus then switches to finding a place to deposit their eggs. They can be quite selective about where to lay – it needs to be moist, but not too wet, and not too dry; it needs to be comfortably warm, not to hot or too cold; and it needs to have the perfect mix of micro-organisms within it for the young larvae to feast on. What better than henhouse poultry manure heap, where it is sheltered from extremes of heat or rain and a little bit of extra moisture and nourishment is added to the pile every night!
Why are flies a problem?
Flies are known to carry and spread a wide range of diseases. They can spread disease among your flock, between neighbouring flocks, and also from the flock to humans. For example, Salmonella, which causes gastroenteritis, can be left on eggs in faecal spots deposited by flies, and the risk is then that these micro-organisms are transferred into human foods. In addition, the flies themselves may reproduce in the henhouse, but over time they will spread out to surrounding areas, potentially causing a nuisance in houses.
How can we manage flies organically?
By using environmental hygiene and trapping in an integrated pest management approach, you can manage fly populations in your backyard flock without insecticides. Regularly inspect your henhouse and maintain it in a hygienic state. Several times per year, clean out the manure that accumulates under roosting perches and replace it with fresh dry bedding. Manure piles are where the fly larvae feed and develop into new flies. By regularly replacing these piles with dry bedding, you can reduce the moisture levels in the bed, making it less suitable for fly development. Similarly, check that your water supply does not drip and make a patch of permanently moist soil suitable for flies and larval development. Fly traps are also a critical part of the organic approach. EnviroSafe fly traps use a bait that is made from food-grade ingredients and is totally non-toxic. They safely remove excess adult flies from the local environment without chemical insecticides. One or two traps hung near the hen house and yards, and re-baited regularly throughout the spring and summer will be enough to keep a lid on fly numbers and reduce the chances of them reaching pest proportions, allowing you to enjoy your poultry without problem flies.