QLLC Midge/Fly Repellent Recipe
One of our lovely Spanish Mustang mares gets sweet itch. Sweet Itch, also called Seasonal Recurrent Dermatitis (SSRD) or more technically, Culicoides Hypersensitivity is a medical condition in equines caused by an allergic reaction to the bites of Culiciodes midges. Midges are tiny bloodsucking insects, not unlike a miniature mosquito. There are many different species of midges, in many parts of the world. They dislike hot, dry conditions, strong wind and low temperatures. They usually attack at dusk and dawn (but can go all day in mild overcast conditions), in woodland near standing or slow moving water. Where we live, on Vancouver Island in the Pacific Northwest of North America, that's practically everywhere from March to November! In many parts of the world the midges bite predominantly along the midline of the back, mane and top of the tail. Our Island midge species bite predominantly along the midline of the belly, and if it gets really bad up the chest, the underside of the neck and the face. It itches like crazy and drives the poor horse mad who bites and rubs itself raw in an attempt to quell the itch. Our poor mare also breaks out in hives from bites by other insects.
After several years of experimentation with various commercial and home made repellents and hundreds of dollars invested in wonderful but expensive sweet itch rugs (from Snuggy Hoods in the UK, we really recommend them if someone wants to go the rug route) which get shredded from rolling on the ground, we are finally successful with a home made repellent.
First, the science for those who are interested. The recipe is based on these research studies:
https://www.ncbi.nlm.nih.gov/pubmed/19670406
http://www.ncbi.nlm.nih.gov/pubmed/21592665
https://www.tandfonline.com/doi/full/10.1080/14786419.2017.1378216
The first two studies showed that a combination of saturated fatty acids referred to as C8, C9 and C10 in a carrier oil were very successful at repelling a range of different insects for periods from 1 to at least 3 days, depending on the insect. It also showed that some even longer chained fatty acids (C11, C12 etc) were even better at it.
The third study successfully tested the mosquito repellent qualities of essential oil pressed from orange peels (sweet orange essential oil).
The silicone oil carrier mentioned in the first study is called Cyclomethicone. It is widely used in cosmetics and hair care products. The straight-chain, saturated fatty acids C8 (Octanoic Acid), C9 (Nonanoic Acid) and C10 (Decanoic Acid) are also called Caprylic Acid, Pelargonic Acid and Capric Acid.
By very happy coincidence, C8 and C10 happen to be the main ingredients in fractionated (liquid) coconut oil, also sometimes called triglyceride. The exact ratio varies a bit depending on brand, but it is usually around 60% to 40%. Coconut oil has the added advantage of having proven, significant wound healing properties, so it also helps if the horse already has skin damage from rubbing and biting. (Whole coconut oil is probably better for this than the fractionated kind, though.)
C9 is a bit harder to come by in smaller (non-industrial) quantities. To make things easier, we tried to find an easy-to-obtain replacement for it. We knew from experimentation that neem oil was also a pretty good repellent, but were not overly fond of the smell of it. So, instead we tried an oil called karanja oil. Like neem oil, it is pressed from the seeds of a tropical tree (Karanja or Pongam), is described as strongly insecticidal and is used in India in similar ways as neem oil in cosmetics and for livestock and garden purposes. It contains a range of mostly C18 and C16 fatty acids.
Finally, and partly because we like things that smell nice, we added sweet orange essential oil. The recipe probably works almost as well without it (for those that need to avoid scents). There are also other essential oils that might have a similar effect, e.g. lemon eucalyptus oil, or cinnamon leaf oil.
So, here is the recipe:
10% liquid coconut oil, 5 % karanja oil in cyclomethicone as a carrier. Add a few drops of sweet orange essential oil if desired.
or
85 ml of Cyclomethicone
10 ml of Fractionated Coconut Oil
5 ml of Karanja Oil
10 drops of Sweet Orange Oil
We apply the repellent once a day, usually late afternoon, so that it will have the strongest effect when the midges are most active at dusk and dawn.
And finally, where to get the stuff: we buy all our ingredients on-line from the Canadian company Sapphire Blue. They sell ingredients and supplies for people making their own cosmetics and have always been a pleasure to deal with for us. You can also buy measuring pipettes, containers, spray bottles etc from them. http://www.saffireblue.ca/shop/
For those that live close enough to us to make it practical, I am happy to make up small batches of our sweet itch/fly spray if you would like to try it out before you order your own ingredients.
After several years of experimentation with various commercial and home made repellents and hundreds of dollars invested in wonderful but expensive sweet itch rugs (from Snuggy Hoods in the UK, we really recommend them if someone wants to go the rug route) which get shredded from rolling on the ground, we are finally successful with a home made repellent.
First, the science for those who are interested. The recipe is based on these research studies:
https://www.ncbi.nlm.nih.gov/pubmed/19670406
http://www.ncbi.nlm.nih.gov/pubmed/21592665
https://www.tandfonline.com/doi/full/10.1080/14786419.2017.1378216
The first two studies showed that a combination of saturated fatty acids referred to as C8, C9 and C10 in a carrier oil were very successful at repelling a range of different insects for periods from 1 to at least 3 days, depending on the insect. It also showed that some even longer chained fatty acids (C11, C12 etc) were even better at it.
The third study successfully tested the mosquito repellent qualities of essential oil pressed from orange peels (sweet orange essential oil).
The silicone oil carrier mentioned in the first study is called Cyclomethicone. It is widely used in cosmetics and hair care products. The straight-chain, saturated fatty acids C8 (Octanoic Acid), C9 (Nonanoic Acid) and C10 (Decanoic Acid) are also called Caprylic Acid, Pelargonic Acid and Capric Acid.
By very happy coincidence, C8 and C10 happen to be the main ingredients in fractionated (liquid) coconut oil, also sometimes called triglyceride. The exact ratio varies a bit depending on brand, but it is usually around 60% to 40%. Coconut oil has the added advantage of having proven, significant wound healing properties, so it also helps if the horse already has skin damage from rubbing and biting. (Whole coconut oil is probably better for this than the fractionated kind, though.)
C9 is a bit harder to come by in smaller (non-industrial) quantities. To make things easier, we tried to find an easy-to-obtain replacement for it. We knew from experimentation that neem oil was also a pretty good repellent, but were not overly fond of the smell of it. So, instead we tried an oil called karanja oil. Like neem oil, it is pressed from the seeds of a tropical tree (Karanja or Pongam), is described as strongly insecticidal and is used in India in similar ways as neem oil in cosmetics and for livestock and garden purposes. It contains a range of mostly C18 and C16 fatty acids.
Finally, and partly because we like things that smell nice, we added sweet orange essential oil. The recipe probably works almost as well without it (for those that need to avoid scents). There are also other essential oils that might have a similar effect, e.g. lemon eucalyptus oil, or cinnamon leaf oil.
So, here is the recipe:
10% liquid coconut oil, 5 % karanja oil in cyclomethicone as a carrier. Add a few drops of sweet orange essential oil if desired.
or
85 ml of Cyclomethicone
10 ml of Fractionated Coconut Oil
5 ml of Karanja Oil
10 drops of Sweet Orange Oil
We apply the repellent once a day, usually late afternoon, so that it will have the strongest effect when the midges are most active at dusk and dawn.
And finally, where to get the stuff: we buy all our ingredients on-line from the Canadian company Sapphire Blue. They sell ingredients and supplies for people making their own cosmetics and have always been a pleasure to deal with for us. You can also buy measuring pipettes, containers, spray bottles etc from them. http://www.saffireblue.ca/shop/
For those that live close enough to us to make it practical, I am happy to make up small batches of our sweet itch/fly spray if you would like to try it out before you order your own ingredients.
