Flies have the potential to transmit diseases and harm animal well-being, especially in densely populated animal production environments, underscoring the need for an effective fly management programme.
According to Dr Didi Claassen, head of technical veterinary support at Afrivet, and Dr Sakhi Nkosi, a technical veterinarian, it is important that farmers have an integrated fly management programme in place that targets fly populations at various phases of development.
What is an integrated management programme?
Claassen says flies do have an important role in the ecosystem because farmers are intensifying farming systems and have a variety of livestock in one vicinity, this gives flies the opportunity with more breeding sites.
“We have increased the numbers of flies, and then they negatively impact our animals and their health. They’re not all bad, but when there are too many [flies in one site] then they become a problem.
The effects that they have can be direct, flies irritating the animals or being a nuisance, similar to when we are swatting flies. They can bite the animals and cause tissue damage,” she explains.
Different stages
Understanding the four stages of fly growth is crucial for farmers because it allows them to implement effective pest control measures and maintain the health and productivity of their livestock, crops, and overall farm environment.
The four stages in the life cycle of a fly are:
Eggs: Eggs are complicated to control. There is no drug that you can give to stop the eggs, but you can limit the breeding grounds. So, breeding sites are where the flies can lay eggs.
Larvae: The second part is if you want to target the larvae specifically, there are products called insect growth regulators. The novaluron, an active ingredient, is a common one that you will be able to find at the co-ops. What that drug does is to prevent the sort of the “squishy” maggot from developing into the “crunchy” fly. So the outside exoskeleton, the outside skeleton of the fly can’t develop if you use those, but you have to apply it to the larvae or where the larvae are.
Pupa: Then thirdly, the pupa – it’s quite new but some wasps can attack the pupa. So, you can buy these wasps. They’re expensive, so it’s not commonly practised.
Adult fly: At this stage, pyrethroids such as deltamethrin may be used for flying insects. There are various products on the market containing deltamethrin. If you can look for something containing deltamethrin that will have the best effect on flying insects. There are surface sprays and some products you can apply to your animal.
“If flies come and land on these products they get in contact with this active ingredient (an adulticide), the fly will die,” says Claassen.
Diseases and impact on cattle
Flies can either be vectors where they carry bacteria like E. coli, salmonella spp., viruses like lumpy skin, or three-day stiff sickness (bovine ephemeral fever) virus and then they transmit it from animal to animal, sort of being a carrier of these diseases, or even anaplasmosis known as gall sickness.
“They can carry pathogens, for example, when Tsetse flies bite, they damage the skin to suck blood, and they then transmit the organism Trypanasoma brucie which is an uncommon disease in South Africa. The risk is having sleeping sickness or nagana, so that’s the negative effect that they can have, either direct or indirect spreading,” Claassen explains.
According to Nkosi, one of the most important processes of cattle farming is nutrition. To produce the precious milk, cattle rely on a consistent and healthy feed intake. If that is disrupted, by flies in this case, it can cause a significant impact on milk production.
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The issue with clustering
“That’s exactly what happens to our bovine friends. The persistent flies not only stress the cattle but also lead to restlessness and that is what our dairy cows go through every day. All this energy expenditure is a double blow to the cattle. It’s a double blow to them, as it diverts their precious energy away from producing milk. And when the cows are confronted with intense fly attacks, they tend to cluster together,” he says.
Nkosi further mentions that cattle find safety in numbers and try to minimise exposure to any threat.
“But this clustering also introduces its own set of issues. It can lead to increased risks of heat stress, which is detrimental to the cow’s health; completely abandoning feed intake,” he says.
Additionally, weight loss becoming so much of a concern due to the constant battle with flies, ultimately impacting the overall well-being of cattle.
According to Claassen and Nkosi, to combat an organism, farmers need to understand the life cycle of the organism and in this particular case, flies.
“The fly life cycle is not a complicated one. The eggs hatch and then you see larvae. So those are the maggots, those little white squirmy things. And then those will pupate, almost like butterflies. From there the pupa, and adult flies emerge. So those are four stages. You have the eggs, the larvae, the pupae and the adults,” he says.
An integrated management programme
To effectively fight flies just goes beyond relying on insecticidal products and a holistic approach should be embraced. This not only reduces chemical costs but also reduces the burden of flies on farms.
There are essential elements to consider in an intervention. Firstly, environmental control which involves taking proactive steps to eliminate or reduce fly breeding sites.
This means managing manure effectively, whether it’s by removing it, spreading it out to dry, or using products that can kill fly larvae.
The holistic approach involves controlling flies on the animals themselves. This can be achieved through the use of dips and pots that contain chemicals effective against flies and ticks like the pyrethroids referred to, deltamethrin.
Keeping livestock fly-free is not just a matter of their comfort, but also their health and productivity.
And finally, strategically placing baits to attract and eliminate flies in these areas is a good move. By doing so, one creates fly-free zones, making life more comfortable for both livestock and farmers.
Advice from the experts
Both Claassen and Nkosi emphasise the importance of starting earlier with the fly management process to avoid peak numbers in December and January.
- Environmental management is important (clean and hygienic).
- Manure management is a very good start.
- If animals die, remove those carcasses, don’t just leave them there for periods.
- Consult with experts such as veterinarians entomologists or agricultural extension.
- Get a specific fly management plan tailored to your specific location and cattle practices.
- Maintain records of fly control efforts that you tried and their outcomes, as this will help you evaluate the effectiveness of your strategies over time.
Make sure that everyone on the farm involved in animal care and farm management is educated about the importance of fly control and the methods being employed.
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