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How To Prepare for Fly Season on Pig Farms

Rowan Burgess |

As winter ends and those first signs of spring emerge, most people are understandably looking forward to some sunshine and higher temperatures. Yet for pig farmers, the developing spring also comes with an impending wave that returns year in and year out. 

The fly season approaches like a dark storm. We all know it’s coming, yet we often feel powerless against it. There’s nothing we can do about flies per se, they are an integral part of our world, but their effects on pig farms can be substantial. Every farm will have flies, but not every farm will be consumed by them in the same way. The difference between preparing correctly and carrying out a systematic plan to keep flies at bay and not can be thousands of pounds in lost revenue.   

What Months Are Flies Most Active on Pig Farms in the UK?

Flies are most active in the UK between May and September when their breeding goes into overdrive thanks to the country’s comfortable conditions. The perfect temperature for flies is relatively high - somewhere between 35℃ and 38℃ - but larval development occurs at a much lower temperature, anywhere from 10℃ and 20℃.  

Because of our changing weather patterns, it’s not uncommon to see flies well into late autumn, with larval development occurring even earlier as we experience warmer early springs.

What Negative Effect Can Fly Season Have On Pig Farms?

An unregulated fly season can cause havoc on pig farms in several ways. While there are individual adverse effects that we’re about to get into, a farm will likely experience all of them if a fly problem is left untreated. 

Disease Transmission

Flies can carry all manner of diseases that can decimate a pig farm. These include E. coli, swine dysentery, African swine fever virus, and salmonella - all of which can prove catastrophic to the human population that consumes the pork or to the pigs themselves. Fly season means more flies, which inevitably increases the possibility of spreading disease. 

Increased Discomfort

While disease might be the most worrying aspect, simple discomfort can have a dreadful knock-on effect. Fly bites can cause lesions or allergic reactions on the skin of pigs, which sometimes means they need to be skinned first at the abattoir, resulting in a loss of profit.    

Increased discomfort can lead to a slump in breeding productivity and weight loss, both of which, when combined across an entire pig farm, have the potential to be economically damaging. 

Reduction in Feed Intake

Numerous factors can lead to a decrease in feed intake. Temperature is one of the most important, with feeding thought to reduce by around 0.1 lb per day for each 1℃ above their thermoneutral zone, while stressed pigs, often because of flies or other nuisances, may reduce feed intake by 1% or 2% depending on the size and age of the pig.

The summer months not only bring higher temperatures that can make the pigs feel uncomfortable, but the increased number of flies can also add an extra layer of stress and irritation.   

Reduction in Profits

This reduction in feeding will undoubtedly lead to a loss in weight, which equates to a drop in profits when it’s time to send the pigs to the abattoir. However, that’s just one aspect where farmers could potentially lose money. As a fly problem grows in size and severity, costs inevitably increase. What might have been a reasonably low cost to address the issue early on has now morphed into something substantially more significant. 

Then there are the enormous costs of handling a significant disease outbreak on a pig farm. Numbers are notoriously tricky to calculate here, but somewhere between £21 and £28 per fattened pig would be an excellent place to start. That might not seem enormous from the outset, but it represents a massive chunk of lost profit when multiplied across the entire farm.  

Tips To Prepare for Fly Season on Pig Farms

The fly season might seem like a desperate battle to hold back the inevitable tide, but preparing correctly and implementing a sustained and clinical approach can make all the difference. You can take a few different avenues, each with benefits and drawbacks.    

Non-Chemical Solutions

While chemicals often produce the fastest and most ruthless results, they’re not for everybody and are certainly not appropriate in every situation. Non-chemical solutions usually take longer but are unquestionably friendlier for the environment and the pigs.

  • Screens - Fly screens and chains can be placed on wall inlets outside or inside and filter the air entering a building, preventing flies from entering. While these are helpful, they won’t stop the flies from entering. 
  • Good Ventilation - When there isn’t enough airflow through a building, condensation and heat build-up makes for an ideal playground for flies. Good airflow will also reduce the moisture in manure, which, again, takes away something flies thrive within. 
  • Clean Up Spilt Feed Regularly - We often overlook the concept of cleanliness when battling against flies. Keeping things clean and tidy and ensuring anything spilt gets cleared up immediately will also help.
  • Manure Management - Pigs produce manure at an incredible rate, and ensuring everything gets cleared up quickly and efficiently is nearly impossible. However, manure lying around for days during warm periods will attract flies in no time. Nobody likes manure management, but doing it frequently can make a huge difference.  

Chemical Control

When a fly problem explodes, chemicals are often the only way to get it back under control. Chemicals are fast acting and incredibly strong, but they are, of course, far from perfect. Some can be used around animals, while others require you to clear a pig pen before using them.  

  • Insecticides - Typical insecticides, such as the Dairy Fly Spray, are easy to mix and use, with a fast knockdown speed that will clear a building of flies in no time. Regardless of its development stage, it can be sprayed directly at any insect.  
  • Larvicides - Larvicides go straight to the source. Eggs and larvae represent a large proportion of a fly population, so attacking them directly with chemicals designed just for that can significantly reduce your overall number of flies. These are usually water-soluble granules easily applied to wet areas but should not come into direct contact with animals.   
  • Adulticides - If larvicides hit the fly in the future, adulticides go straight for the present. Depending on the severity and situation, you can apply them in several ways; baits, sprays, paints, or mists. They are almost universally fast acting and can clear a large room of adult flies in no time. 

Physical Control

Physical control methods range in style but typically involve traps or bombs left for some time. They are usually much more environmentally friendly than the chemical approach but might struggle with more significant fly problems.  

  • Smoke Bombs - Smoke bombs are great if you want to leave something to its own devices. Quiet yet deadly, smoke bombs usually don’t have an actual spark, making the word bomb a little misleading, but they work by slowly releasing smoke lethal to flies. This is a great way to make sure every nook and cranny is taken care of and doesn’t take much of your time.  
  • Electric Fly Killers - Electric fly killers used to be common around homes but have gone out of fashion. However, on pig farms, they are a great option and work simply by attracting flies to their fluorescent light before zapping them.  
  • Fly Traps - Fly traps aren’t the most pleasant things to look at, hence why we rarely see them around homes, but in farm buildings, they are a quick, easy, and environmentally friendly way of killing many lies. Many can hold thousands of flies within their pouches, and new versions are biodegradable, making disposal easy.  

Frequently Asked Questions

Do Pigs Cause Flies?

While pigs don’t cause flies, the area where they reside and the manure they produce create an ideal environment for flies to thrive in. Any animal, including ourselves, would attract flies without proper sanitation and cleanliness. Pigs are clean animals, but their homes are not.  

Final Thoughts

A substantial fly problem can feel like a mountain to climb, but there are several options to address it, many of which we've mentioned. Getting a handle on flies in the build-up to fly season is imperative. Wait too long, and you’re always playing catch-up. Dalton offers various fly control products to help you formulate the perfect plan that works for you and your farm. Fly season is just around the corner. Are you ready?