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May. The first warm afternoon after many cold days. You lead your horse out to the paddock – and within five minutes, you're back because the horse starts nervously shaking its head and tail, trying to rub against the fence. In the afternoon, the same scenario plays out in the arena, only worse – the horse can't focus, it's tense, nipping, trying to bite its own flank.
The insect season in Poland usually begins in late April and continues until September. For a rider, this is not just an inconvenience – it's a real deterioration in the quality of the horse's work, a risk of allergic reactions, and a fundamental welfare challenge. A good repellent in season becomes equipment as essential as a saddle and bridle.
In this guide, we'll walk you through which insects attack horses in Poland, which active substances really work, how long they last, and how to apply repellent correctly – so your horse can work calmly even during peak season.
Seasonal Enemies – Who Exactly Does Repellent Combat?
The effectiveness of a repellent depends on the specific enemy it targets. In Polish seasonal conditions, horses are attacked by five main groups of insects – and not all are equally susceptible to the same substances.
Stable flies (Stomoxys calcitrans). Most troublesome in summer. They bite painfully – especially the horse's legs, belly, and flank. They appear in large numbers in and around the stable. They breed in damp, dirty bedding – controlling their breeding source (cleaning stalls, removing wet bedding) is as important as repellent.
Blackflies (Simulium). Tiny black insects that attack in swarms in early spring and summer near rivers, lakes, and damp meadows. They bite around the ears, belly, underbelly, and legs. The horse's reaction can be strong – swelling, itching, sometimes allergic reactions. In May in Poland, blackflies are often the number one problem.
Mosquitoes. Classic, mainly attacking in the evenings and at night. Less severe than blackflies, but in large numbers (around standing water, meadows) they can disrupt a horse's work.
Horseflies (Tabanidae). In summer – large, fast, biting very painfully. They most often attack the legs, underbelly, and neck. They frighten horses to the point that they can flee in a panic – this is a real safety risk.
Tropical external parasites (ticks, some mites). Less common than in other climates, but present – especially during trail riding in forests.
Conclusion: a good repellent should be effective against a wide spectrum of these insects, with an emphasis on blackflies and stable flies – as these are most often the ones that disrupt work.
Active Substances – What Really Repels and What Just Smells Nice
The market for horse repellents is flooded with a variety of products, but only a few active substances are effective. The rest is often marketing, "natural formulas" with limited or short-lived action.
DEET (N,N-diethyl-m-toluamide). A classic. Used for decades in human and animal products. Very effective against a wide spectrum of insects, including blackflies, mosquitoes, and flies. Lasts 3–6 hours depending on concentration. In premium equestrian repellents, it remains one of the main effective ingredients – including in Absorbine UltraShield 946 ml, a classic of the American horse repellent market.
Icaridin (picaridin, KBR 3023). A newer alternative to DEET, gentler on the skin, equally effective. Increasingly popular in premium products.
Permethrin. A synthetic substance with not only repellent but also directly insecticidal properties. Very effective, especially in "spot-on" repellents (applied pointwise, on the horse's neck). Lasts 7–14 days. Caution: highly toxic to cats, so used with care in stables with cats.
Citronella (lemongrass oil). A natural substance with moderate repellent action. Short-lived (1–2 hours). Often used in "natural" formulas. Actual effectiveness is lower than DEET or picaridin – it works, but requires more frequent application.
Essential oils (eucalyptus, lavender, mint). Act mainly by scent. Moderate effectiveness, short duration. Good as a supplement, but not as a primary repellent during peak season.
Vinegar and homemade natural formulas. Popular in horse communities as a "safe alternative." Much lower effectiveness than commercial products, very short duration. Can be a supplement for a horse in the stall, but not sufficient for the paddock during full blackfly season.
What to buy first: a repellent with DEET, picaridin, or permethrin as the main ingredient. Premium brands usually combine two to three active substances for a full spectrum.
Application Form – Spray, Gel, Spot-on, or Roll-on
Spray. The most popular form. Allows quick application of repellent to a large area. Disadvantages: some of the product goes into the air, consumption is higher, some horses react to spraying. Good for daily use before training. In this category, a proven Polish choice is Asekor Fly 750 ml – a broad-spectrum product, valued for its effectiveness and affordable price in season.
Gel / Cream. Allows precise application of repellent to specific areas (ears, face, delicate areas). Less consumption, longer local action. Ideal for ears and face – where spray should not go near the eyes.
Spot-on. Point application of a few drops of the product on the horse's neck. Works systemically (the substance spreads through the skin throughout the body) and for a very long time – 7–14 days. The number one choice for horses in constant contact with blackflies and flies – especially pastured horses.
Roll-on / Sachets. Convenient for trips, field expeditions, for the training bag. Smaller packaging, easy application to the horse's side.
Multi-layer strategy: for a horse in an intensive work season, a combination works best – spot-on every 7–10 days as a base for long-term protection + spray before each training for reinforcement + gel for face/ears in delicate areas. For stables with several horses or riders planning for the entire season ahead, Absorbine UltraShield in the 3.8 l version is an economical solution – an economical package sufficient for many weeks of regular work.
How to Apply Repellent Correctly
Before first use. Perform an allergy test – apply a small amount of the product to the horse's side (a small area, approx. 5x5 cm) and observe for 12–24 hours. If redness, swelling, or itching appears – the product is not suitable for this horse.
Clean surface. Repellent works on clean, dry skin. Applying to a muddy, sweaty horse – significantly weaker effect. Before training: brush the horse thoroughly, then apply.
Full coverage. Insects attack all exposed areas. Apply to: legs (from hooves to belly), belly (especially along the midline), neck, side of the chest, under the tail. Face and ears – always with gel or roll-on, never spray.
Avoid eyes, nostrils, wounds. Active substances in repellents can irritate mucous membranes – be especially careful around the eyes and inside the nostrils.
After training. Wash off sweat – repellent mixed with sweat often loses effectiveness. For a horse that will return to the paddock, reapply after washing and drying.
In heat. High temperatures shorten the duration of repellents. In heat of 30°C+, apply every 2–3 hours instead of every 4–6.
Additional Protection – Insect Net, Fly Rugs, Hats
Repellent is not everything. During peak blackfly and fly season, it's worth considering additional mechanical protection:
Anti-fly net for ears. Placed on the bridle during work. Protects the ears, the most sensitive part of the horse, from biting. Inexpensive, very effective locally.
Fly masks. Worn in the paddock or stall. Protect the face, eyes, and ears. Good masks have a mesh density that stops blackflies.
Fly rugs. Light rugs made of breathable material that protect the horse's torso. Ideal for the paddock – the horse is shielded from the back, belly, and parts of the legs, but in thermal comfort (breathability). In the category of fly rugs and masks, you will find a full range of models – from light paddock mesh to full seasonal rugs with head and neck protection.
Stable fans and ventilators. They help in the stall – insects don't like moving air. A one-time investment that works throughout the season.
Most Common Mistakes in Insect Season
Mistake 1: saving on repellent. A cheap repellent for 30 PLN that lasts an hour actually costs more than a good repellent for 90 PLN that lasts 4 hours – because it requires 4 times more frequent application.
Mistake 2: application only before training. A horse standing in the stall and paddock is attacked 23 hours a day. Repellent should also protect on rest days.
Mistake 3: ignoring allergic reactions. If the horse has redness after application – do not continue with the same product. Change brand or formula.
Mistake 4: neglecting stable hygiene. Cleaning stalls, controlling bedding moisture, eliminating lingering crops – this reduces the insect population at the source. Repellent is not a substitute for a clean stable.
Mistake 5: using repellents for dogs or humans. Some substances (e.g., permethrin in high concentrations) safe for dogs are deadly to cats; others suitable for humans may be too aggressive for a horse's skin. Always use repellent dedicated to horses.
Most Frequently Asked Questions about Repellents
Are repellents safe for horse skin?
Reputable brands (Absorbine, NAF, Pharmaka) are dermatologically tested. A small percentage of horses may have individual allergic reactions – hence the recommendation to test on a small area before full application. Safety depends on the quality of the product, not on "naturalness" – a natural essential oil in high concentration can be more irritating than a professional pharmaceutical product.
Can I compete after applying repellent?
Yes, external repellents are not on the list of prohibited substances by FEI or PZJ. However, some repellents with strong essential oils may affect the horse's smell during anti-doping control – for high-level competitions, it's worth checking the product's ingredients before starting.
How much does a repellent season cost for one horse?
For a horse in an intensive season (daily work + paddock): approx. 300–500 PLN per season (April–September). This usually includes 2–3 spray bottles, 1 spot-on product, 1 face gel, possibly 1 mask.
Are homemade repellents (vinegar, water + oil) effective?
To a very moderate extent – mainly for individual mosquitoes or flies in the stall. They are not sufficient for the paddock during blackfly season. They can be a supplement for a horse in the stable, but not a substitute for a professional product.
What to Do Now
The best first step before the season is to assemble a basic kit – spray for daily use, spot-on for long-term protection, gel for face and ears. A full range of products for horse insect protection – including a complete range of repellents, masks, rugs, and sensitive skin care products – can be found in one place at the Equishop store. The most important rule: start early. The first application before the peak season – late April, early May – allows the horse to get used to it and provides better tolerance than intervention in July when blackflies are already attacking.
If the topic of horse protection during the season is more important to you than just insect control – we also recommend reading our article on spring resumption of horse work, which fits into a broader plan for a conscious season.
