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How To Prepare for Fly Season on Poultry Farms

Rowan Burgess |

As temperatures start climbing, poultry farms must prepare for something that could wreak havoc on poultry and profits: fly season. 

Good management strategies are defensive and proactive as well as year-round. By the time the sun’s out, and you’ve seen the first fly, you’re already behind the curve. 

Controlling flies requires a combination of preventative measures before the fly season and active control programmes during the warmest months. 

But there’s no one-size-fits-all solution for fly season. You’ll need different strategies depending on when during the season it is, the level of infestation, and more. Here’s what to know. 

When Is Fly Season in the UK?

Usually, the fly season in the UK is from April to October. However, the British seasons are not always the most predictable.

With the quirky British weather plus the added impact of global warming, flies can appear much earlier than April, and certain species persist even into November. 

Each year varies depending on the type of winter and spring. A cold winter followed by a late spring can delay the arrival of flies to May. Beware of a very mild winter, as you may see flies as early as February if the conditions are warm and temperate.

The fly lifecycle can speed up when it’s hot, so an early spring, followed by a hot summer or a heatwave, could cause a population explosion. However, exceptional temperatures like those of 2022 help diminish the insect population.

What Negative Effect Can Fly Season Have On Poultry Farms?

The fly season can spell disaster for poultry farms that haven’t prepared adequately. The adverse effects could impact your poultry, profit, and peace of mind.

Increased Discomfort

Flies don’t attack poultry in the same way that they do cows or horses, but they can stress the birds and cause discomfort. Stress leads to reduced egg protection or a lower meat yield.

Chickens are also vulnerable to fly strikes when an adult fly lays eggs on the bird. The eggs feed on the chicken’s flesh when they turn into maggots.

Spreading Diseases

Flies are a significant vector of bird and human diseases, including botulism, salmonella, strains of E-coli, Coccidiosis and Avian influenza. 

Avian Influenza, or bird flu, is causing particular problems in the UK with the largest outbreak ever. Because avian flu is present in the wild bird population, the UK government has imposed restrictions on all poultry keepers.

Flies transmit disease by carrying parasites, bacteria, or viruses on their bodies or through their mouthparts after contacting or eating infectious materials. Chickens become infected by eating flies or by direct contact.

Fly populations act as reservoirs for disease on poultry farms, affecting not only the flock but also neighbouring properties. And with global warming, the increase in the fly population means a worsening of disease spread

Community Disturbance

As house building increases in rural areas, more and more people are moving to the countryside with a somewhat sanitised and sentimental view of what farming involves. 

However, farming is noisy, roads are muddy at certain times of the year, and livestock farming, in particular, is smelly and industrial, with large volumes of manure and plenty of lorry traffic.

People will complain about all these issues but will mainly moan about the smell and an increased fly population with the attendant risk of disease if they live near a poultry farm. 

In truth, the poultry farm may not be responsible for a fly infestation. Still, it’s a favourite culprit for domestic homes to point the finger at if they’re experiencing an increased fly density during the summer. 

Fly control protocols are a requirement of an environmental health permit.

Fly infestations cause reputational problems for farmers and may create difficulties if the farm wants to change its layout or expand. Poor community relations are common in areas with large, intensive poultry farms.

Monitoring fly populations twice weekly during the fly season helps repel complaints about insect infestations. 

There’s no defined threshold for fly populations in the legislation, so it’s a question of managing complaints with evidence of good practice and proper fly management strategies.

Visit from EHO

A visit from the local Environmental Health Officer is possible if there’s a complaint from a nearby resident about smell and fly populations.

An EHO can come onto the farm and investigate, assess, and ultimately control environmental factors that pose a risk to health and well-being.

EHOs will visit a farm to ensure the proper protective measures are in place and to enforce appropriate legislation to protect environmental and human health.

The impact of failing to control flies is quite significant; it carries a fine of up to £10,000 and potentially a six-month prison sentence under the Clean Neighbourhoods and Environment Act 2005.

Profit Shrinkage

An unsanitary poultry farm without adequate fly control strategies will affect the birds’ health and, ultimately, their yield and profitability.

Managing disease outbreaks in the flock is expensive in terms of increased veterinary costs, additional labour and higher-than-usual bird losses.

The bad publicity of a large farming organisation that has experienced fly control problems appearing in the media can have a knock-on effect on the company’s profits.

Tips To Prepare for Fly Season on Poultry Farms

Different methods will be necessary depending on when in the season you’ve caught the issue. 

Non-Chemical — Sanitation and Fly Exclusion

  • Manure, Water, and  Moisture Management – removing the waste at least twice weekly breaks the breeding cycle. Fresh poultry manure contains 75%-80% water, making it ideal for fly breeding. Reducing the moisture content to 30% or less helps eliminate fly breeding, plus it's easier to store and lighter to transport. Avoid piles or heaps. Spread the manure in thin layers.
  • Screens – screens in entrance doors, windows, and inlets are a physical barrier to deter flies without interrupting airflow and ventilation. Chain curtains are an alternative in doorways.
  • Fans – flies will not move against the wind, so strategically located fans deter them from entering sheds and housing. They also help regulate temperature and promote airflow on hot days.

Chemical Control

  • Insecticides – insecticides offer a targeted method of killing large adult fly populations via mechanical spraying or cold fogging. Cold fogging turns a liquid solution into airborne particles using high pressure.
  • Larvicides – larvicides target the larval stage of the fly’s lifecycle and are for application in breeding areas. Effective fly control should target all stages of the fly’s lifecycle and not just aim at the adult population.
  • Paint – some insecticides can be both sprayed and painted. Paint stripes on the walls and ceilings of poultry sheds. Fly paint kills by either contact or ingestion. Most insecticides have a long-lasting residual, meaning they continue to work for days or weeks after application.


  • Hanging Paper – fly papers are sticky strips of paper that harvest flies with a fly attractant substance. Sticky strips have the advantage of working 24/7 and are cost-effective, killing flies without using pesticides.
  • Zapperselectric fly zappers of killers have a more design-friendly aesthetic than other forms of physical fly control. Zappers kill flies instantly and work 24/7, avoiding the use of pesticides. However, you’ll need to factor in the ongoing cost of electricity.
  • Fly Traps – baited fly trap bags can hold as many as 20,000 flies, attracting flies within a radius of up to 10 metres. Flies go in and can’t escape. Just add water to activate.
  • Smoke Bombs – easy to use and fast-acting. Light the wick, and the fumes permeate the entire area, including the nooks and crannies of hard-to-reach roof areas. Smoke bombs are not suitable for large infestations.                         

Frequently Asked Questions

What Months Are Flies Most Active in the UK?

Flies are usually the most active between April and October. However, the UK is notorious for all four seasons in one day, so unusually mild winters and early, warm springs can herald their earlier arrival.

Flies, don’t look at the calendar!

Final Thoughts

Deterring flies on a poultry farm is a year-round task, but the arrival of the warmer months means it’s time to double the effort.

Effective fly management programmes promote poultry health and protect egg and meat yield, helping to optimise productivity—ineffective fly control results in lower profits and the potential for disease and complaints from neighbouring properties.

Dalton Engineering stocks everything for the poultry farmer to manage fly populations. Shop today for fly control products for large and small poultry farms.