30/06/2025
🪰 Horse Flies, Fly Sprays & Frustration: Why Nothing Seems to Work (and What Might Actually Help)
We all love the long, warm days of summer… until the horse flies arrive.
If you're feeling defeated by the constant battle with biting flies – especially the big, aggressive ones that leave your horse jumping, stamping and stressed – you're not alone. Even the best fly sprays can seem useless on those hot, still days when horse flies are out in full force.
So let’s take a closer look at what’s really going on.
Why are horse flies so persistent? Why doesn’t your fly spray seem to help? And what can we realistically do to protect our horses?
What Makes Horse Flies So Awful?
Horse flies are part of a group of biting insects called Tabanidae. Unlike midges or mosquitoes, which use a fine, needle-like mouthpart to draw blood, horse flies take a much more brutal approach. The females slice into the skin with scissor-like mouthparts, then lap up the blood. Yes, it’s as unpleasant as it sounds – and that’s why their bites are so painful.
Only female horse flies bite, and they need a blood meal in order to reproduce. They’re drawn to:
• Body heat
• Sweat and moisture
• Carbon dioxide from breathing
• Dark colours
• Movement
So if your horse is warm, dark-coated, sweaty, or simply standing still on a muggy day, they’re a prime target
Why Doesn’t Fly Spray Always Work?
Many horse owners feel like they’re spraying their horses constantly, only to watch the flies return within minutes. That’s not your imagination – there are a few reasons fly sprays often seem to fail.
Most fly sprays fall into two main categories:
1. Chemical repellents or insecticides
These include:
• DEET – This confuses the fly’s ability to smell or sense the horse. It’s commonly used in both human and animal repellents.
• Permethrin or Cypermethrin – These are synthetic versions of natural pyrethrins (insecticides made from chrysanthemum flowers). They can kill or repel insects on contact by disrupting their nervous systems.
Sprays with these ingredients are usually longer-lasting and more effective – but they also break down quickly in sunlight, or when your horse sweats, rolls, or gets wet.
2. Natural-based repellents
These are usually made with essential oils like:
• Citronella
• Neem
• Eucalyptus
• Tea tree
• Lavender
While they smell nice and are less harsh on sensitive skin, natural sprays wear off quickly – often within 30–60 minutes – especially on hot, sunny days.
So if your fly spray isn’t working, it may be because:
• The ingredients aren't strong enough for horse flies
• The spray is wearing off quickly due to sweat or sun
• Your horse is very attractive to flies (yes, really – some just are!)
What Does Work (Realistically)?
Here’s a look at some of the better-performing options and techniques – backed by both science and real-world use
✅ Stronger fly sprays and repellents
• Coopers Fly Repellent Plus – Combines permethrin with tea tree oil; tends to last longer and is vet-approved.
• Deosect – Prescription-only and very effective against horse flies. Must be diluted and used carefully.
• Nettex Summer Freedom Salve – Great for protecting sensitive areas and useful against midges too.
Even strong repellents may need to be reapplied once or twice a day during peak fly season.
✅ Physical protection
• Fly rugs – Especially ones with belly flaps and neck covers. Zebra-striped rugs have actually been shown in studies to confuse flies and reduce landings.
• Fly masks – Make sure they have ear and nose protection if needed.
• Fly boots – For horses getting bitten around the legs or constantly stamping.
✅ Timing and turnout
• Try to avoid turnout during peak fly hours (roughly 10am–4pm).
• Many horses are more comfortable out early in the morning or in the evening, when horse flies are less active.
• If you have the option, stabling with a fan can help – flies struggle to land in moving air.
🪤 Could a Horse Fly Trap Actually Help?
Yes – especially an H-Trap. These clever, chemical-free devices are designed specifically to catch and remove horse flies from your yard or paddock.
Here’s how they work:
• The trap has a large black ball that heats up in the sun and gently sways, mimicking a warm animal.
• Female horse flies are drawn to the movement and heat, thinking it's a horse.
• When they realise it’s not food, they instinctively fly upwards – and get caught in the cone-shaped top, where they can’t escape.
🧪 Scientific studies and real-world testing have shown that these traps can significantly reduce horse fly numbers – by 50% to 90% in some areas, depending on fly pressure and placement.
Pros:
• Chemical-free and safe around animals
• Reusable and weatherproof
• Breaks the breeding cycle over time
• Highly targeted to horse flies (not midges or stable flies)
Tips for best results:
• Place the trap in a sunny, open space, away from your horse’s shelter – this draws flies away.
• One trap covers around 1 hectare (2.5 acres), so you may need more than one for larger areas.
• They work best before the population explodes, so early summer placement gives the best results.
They won’t replace sprays or rugs completely – but they do make a noticeable difference when used as part of a full fly control plan.
✅ Other Helpful Options
• Supplements like garlic (in moderation), brewer’s yeast, or cider vinegar may help reduce fly attraction for some horses.
• Fly traps or sticky ribbons placed away from horses can help reduce fly numbers.
• Paddock hygiene – removing droppings regularly, managing standing water, and keeping muck heaps well away from your horses.
Horse flies aren’t just annoying – they can cause real problems. Bites can lead to:
• Swelling and pain
• Allergic reactions or hives
• Skin infections
• Reluctance to be handled or ridden
• Even eye damage if flies swarm around the face
There’s no magic bullet, but combining different methods – stronger sprays, protective gear, paddock management, and traps like the H-Trap – can seriously reduce fly-related stress for you and your horse.
Have you found a secret weapon that actually works?
We’d love to hear what’s worked (or not!) on your yard 💚
* If you found this informative or useful please do give it a share to help other horse owners 💚