I use a quart of vinegar with a couple of drops of dish detergent, 1 tsp. citronella essential oil, 1 tsp. lemongrass essential oil and 1 tsp lavender essential oil. It works for a while.
These formulas are from:
http://www.gentlespiritllamas.com/html/tips/insects.htm
1:
This spray is said to last all day and can be “sweetened” by adding a few drops of lavender.
4 oz. Skin So Soft from Avon
1 oz. Citronella oil – health food grade
½ oz. Eucalyptus oil
1 T vanilla
12 oz. Cider vinegar
12 oz. Water
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#2:
¼ cup of Dawn dish soap
1 and ½ cup vinegar
1 capful of Skin So Soft
Mix with one quart of water and it is ready to spray
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#3:
2 T of eucalyptus oil
2 T of Skin So Soft
Mix with one quart of water and it is ready to spray
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#4:
10 drops each of good quality pennyroyal and citronella
¼ cup of almond oil
a few drops of glycerin
Can be used in this mixture or added to water. You must keep shaking the mixture if added with water.
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#5:
2 tsp tea tree oil
2 tsp liquid vitamin E
4 oz of regular Desitin
Mix together. It will be the consistency of honey. It is said to work well on those insect irritated bare spots most commonly seen on the ears and nose.
Some folks swear by additives to the diet. An “old” horse remedy advocates adding apple cider vinegar into the water source. (It is said that white vinegar will have the same result.) It might take a short time for the alpacas and llamas to adjust to the taste but within three weeks; the number of flies on the animals should have lessened significantly.
Fresh garlic seems to have the ability to change our smell and taste and insects tend to avoid it. Fresh garlic is also considered an excellent antibiotic.
The complete B-Complex is said to also have the ability to change our smell and taste.