Flies Show Horse Color Preferences

In the world of blood-sucking tabanid flies, a white horse is not nearly as attractive as a brown or black horse, noted a group of researchers from Hungary, Spain, and Sweden.

This interesting tabanid tidbit is likely to be welcomed by white horses and their owners, given that being white has its disadvantages; white horses are more sensitive to solar radiation, leading to skin cancer and deficiency of the visual system, and are easily detected by predators.

Based on field experiments and a small number of choice experiments, the researchers found that white horses were less attractive to blood-sucking tabanid flies (including horseflies and deerflies) partly because of the polarization of light.

That is, horses with light coats reflect light with lower degrees of polarization than dark horses. As the authors explained, light colored horses have more backscattered light from the hair and skin tissues than dark horses, which ultimately reduces light polarization.

This research is important because blood-sucking tabanid flies are able to spread diseases such as equine infectious anemia (EIA).

The study, "An unexpected advantage of whiteness in horses: the most horsefly-proof horse has a depolarizing white coat," will be published in the Proceedings of the Royal Society of London; Series B, Biological sciences. The abstract is currently available on PubMed.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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