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Zebra Stripes May Act as Natural Insect Repellent

A zebra in a Florida zoo (file photo)

The stinging, disease-spreading bite of a blood-sucking horsefly may be the key to the mystery surrounding how zebras got their stripes.

Findings of a new European study suggest that zebras evolved their unique markings because the narrow black and white vertical stripes are not attractive to horseflies, which are found across Africa.

The international team of scientists says its findings hinge on a new understanding of how the insects perceive the light reflected by the animal’s coat.

Scientists conducted a series of tests to see how horseflies, also known as tabanids, reacted to the light reflected by solid black, brown-grey and white horses, as well as the vertical stripes of a zebra. They say they were surprised when the striped coat attracted far fewer flies than the solid coats, with the thinnest stripes being the most disruptive for the insects.
The flies most preferred the “flat” horizontally polarized light waves from a dark horse coat, whereas the unpolarized light reflected from a white horse was among the least popular.

Zebras, close equine relatives of the horse, are native to Africa.

The new study is published in the Journal of Experimental Biology.