website How To Compare Fly Spray

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How To Compare Fly Spray

Posted by Animal Care Team on
How To Compare Fly Spray - Absorbine

At Absorbine®, we hang our hats on the fact that our products work. And here’s the deal – not all fly sprays work the same, because they can have drastically different formulas. Our premium UltraShield® Fly Sprays work so well because they contain high-quality, advanced, meticulously formulated ingredients at effective levels. But we aren’t asking you to just take our word for it. Here, we’ll help decipher how to compare fly spray labels yourself. The labels are full of information, but what does it really mean? Let’s see if we can break it down and discover how to compare fly spray labels so you can make informed purchases and end fly frustrations this season!

Product Claims

First, everything written in the bigger font size tells you what the product does – in marketing lingo, these are the product claims. Manufacturers can’t just say whatever they want on the labels though. Fly sprays are highly regulated for safety and efficacy, and the language used on label claims is equally regulated. We recommend you trust a fly spray manufacturer who follows the rules, rather than one run out of a garage somewhere – the safety of you and your horse are so important.

Ingredient Listing

The small type you see under those claims, at the bottom of the label on the front of the product, is where the rubber really meets the road. This language lists active ingredients, synergists, inactive ingredients and the percentages of those ingredients. The types and levels of active ingredients can vary among fly spray products, but they make a big difference in helping you understand how well you can expect a fly spray to work and which ones are worth your money.

UltraShield EX Bottle

Active Ingredients

Actives are the ingredients that have insecticide (killing) and repellent power. Many of the most commonly used actives have both insecticide and repellent characteristics. There are two forms of actives, namely natural and synthetic. The most common actives are pyrethrins, permethrin, resmethrin, tetramethrin, and cypermethrin. More recently, picaridin has come on the market for use as a combined horse and human insect repellant spray.


  • Pyrethrins are natural and are derived from certain species of chrysanthemum. They provide very quick knockdown – in other words, they kill the insects quickly. However, pyrethrins can be broken down by sunlight, so special synergists are often added to protect and extend the effectiveness of a pyrethrin formula.
  • Pyrethroids are synthetic forms of pyrethrins. The most common pyrethroids are permethrin, cypermethrin, tetramethrin, and resmethrin. Pyrethroids are not as easily broken down by sunlight, so their effectiveness can last for several days. Both pyrethrins and pyrethroids have a long track record for effectiveness and animal safety on horses.
  • Synergists Many of the actives listed above work best with a synergist. Synergists are chemical agents used in conjunction with the actives to enhance killing power and provide longer-lasting protection.
    • Piperonyl Butoxide kills by attacking the fly’s central nervous system and provides a quick knockdown. It kills on contact when used with synergistically with pyrethrin.

Comparing Levels of Active Ingredients

How to Compare Fly Sprays

When you compare fly spray, it’s important to look beyond the price tag and focus instead on the list of the active ingredients and the levels of those ingredients included in the formula. But you need to look closely, the amounts are usually in percentages, and those percentages are relatively small so it’s hard to see the difference.

Let’s say you have brand A and brand B. You look at the active ingredients and their percentages and see that brand A contains 0.05% permethrin and brand B contains 0.50% permethrin. That means there is 10 times more of the active ingredient in brand B. Which brand do you think will be more effective? Continue this comparison for each of the active ingredients listed and also look for the number of active ingredients in each formula to make an informed choice among the different brands of fly spray available. It’s easy to be disappointed by brands with very low levels of actives and therefore a lower price. With fly sprays, as with most things in life, you really do get what you pay for. You can read UltraShield fly Spray labels on each of the product’s pages. We encourage you to compare them to other manufacturer’s labels.

Water-Based or Oil-Based?

Another point when you go to compare fly sprays is whether they’re water-based or oil-based. There are advantages and disadvantages to both. Water-based fly sprays are not an irritant for most horse’s skin, and won’t attract dirt or dust. However, water-based sprays should also include synergists in the formula to keep them from breaking down in environmental conditions (sunlight, rain, sweat, etc.). Oil-based fly sprays quickly stick to the hair coat and provide rapid knockdown of insects by suffocating them when sprayed. However, due to the nature of oil, oil-based fly sprays will attract dirt and dust. In addition, oil-based fly sprays can irritate the skin of sensitive horses and some horses are prone to burning if they are sprayed with an oil-based product and then turned out in the sun. It’s not always easy to determine if a fly spray uses a water or an oil base. The easiest way to tell is to look at the bottom of active ingredient listing. If you see the statement, “Contains Petroleum Distillate” then you know the product is oil-based.

Ready-to-Use & Concentrates

You will be able to find on the label a section that tells you whether the product is “ready-to-use” or is a concentrate. Ready-to-Use products are good because they are already mixed to proper, effective levels. If you chose a concentrate, be aware that mixing fly spray to levels outside of what the label instructs, or adding additional ingredients may put your horse in harm’s way. You never know how two ingredients are going to interact with each other.

All-Natural Fly Repellents

Another option to consider when you compare fly spray are those which use natural ingredients. All-natural fly sprays provide a safe, alternative to chemical sprays. They are generally environmentally friendly, non-toxic, and insecticide-free. Natural fly sprays commonly use natural oils known to repel insects such as citronella, geraniol, eucalyptus, thyme, cedar oil, lemongrass, rosemary oil, and clove oil. You’ll notice on the label of natural fly sprays that they do not contain insecticides. This means that natural fly sprays will not kill insects. Instead, natural fly only repel insects. Because of this, natural fly sprays will not be effective at reducing the insect population around your barn. The ingredients in natural fly sprays also breakdown more quickly than their chemical counterparts and so they must be reapplied often, usually every 8 hours. However, natural fly sprays can be a great option for people looking to go green, or for people who may want to use fewer chemicals when the bug population is low in the early spring and late summer and fall.

UltraShield EX Bottle


Take it from the manufacturer – applying a fly spray correctly will save you time and money. Here are some of the instructions on the UltraShield EX label:

  • Apply enough product to be effective
    • Waving a mist of fly spray over your horse like perfume is not going to work. Apply up to 2 ounces of product per application. This equates to around 45 pumps of the spray bottle.
  • Apply to a clean horse. You don’t want to apply your fly spray to mud or dust.
  • Shake well before you start applying.
  • Cover every inch of your horse. The flies will find untreated areas.
  • Cover the entire hair shaft. As you spray, you can ruff the hair against the growth. This will make sure the liquid covers well. Follow up by brushing over the coat to even out the coverage.
  • Do not store your fly spray in the sunshine as it will degrade the active ingredients.
  • Use a soft cloth to apply to the face or sensitive areas.

UltraShield EX Bottle

Use Restrictions, Warnings, Precautions

Any registered insecticide will come with warnings on the label. These are obviously placed there with yours and your horse’s safety in mind. There may also be additional instructions about the safe disposal of packaging or unused product. For instance, it is known that bees and aquatic animals are especially sensitive to insecticides. For this reason, never dispose of insecticide down a drain or pour it into a waterway. Do not spray near bee hives or where bees are collecting pollen or else you risk killing bees.

We’ve collected these tips for informational purposes only. Always follow the label instructions closely for the particular insecticide product you are using.

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