When uniformly coloured horses were dressed in "zebra coats" the flies made far fewer landings on the striped areas but were not kept away from the uncovered head. Even Kipling would have struggled to construct a Just So story as unlikely as the discovery that the zebra evolved stripes to make flies go splat.
The evolution of the zebra's black & white coat has intrigued scientists for years. Therefore, it is unsurprising that zebras utilise both behavioural defences and morphological striping to avoid horse flies.
This does not happen with domestic horses, which are without stripes.
The objective of the black-and-white markings has always been a mystery.
The researchers recorded three captive plains zebras and nine monochromatically colored horses in adjacent fields in the United Kingdom where European tabanids (horseflies) naturally occur. Researchers also found that horses and zebras react differently to flies. I've wondered why zebras had stripes ever since I learned zebras existed. Perhaps the animals' signature coats help them camouflage, facilitate social signalling, or keep zebras cool. Scientists from the University of California and the University of Bristol have conducted a series of experiments to figure out why the stripes of a zebra foil biting flies.
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However, once the flies are close to the zebras, they tend to fly past the zebra or bump into it, that indicates the stripes might disrupt the flies' ability to control the landing. In other words, there seem to be "enormous benefits to having a striped coat for a horse", Caro tells Ed Yong of theAtlantic.
African horse flies carry diseases such as trypanosomiasis (which cause fever, headaches, joint pains and itching and can later on include behavioural changes, confusion and poor coordination) and African horse sickness that causes wasting. Scientists will explore whether stripes mess with bugs' optic flow and what types of patterns might deter more of them.
University of Bristol biologist and study co-author Martin How also said stripes may dazzle flies somehow once the insects venture close enough to see them with their low-resolution eyes.
Moving forward, the researchers plan to tease out how different variables-like coat thickness and subtle differences in pattern-might impact hungry flies. This excluded any differences in behaviour or smell between horses and zebras. "I wouldn't want to suggest that horse-wear companies sell striped livery for their riders yet", he explains.