Why do zebras have stripes? Flies may have the answer

Zebra stripes have long amazed the public and researchers alike. What role could black and white stripes possibly serve an animal on the African savannah? One benefit seems pretty clear, though. They repel flies. In a recent study published in Scientific Reports, Kaia Tombak and her colleagues tried an experiment. They hung animal pelts in a plexiglass box on the Kenyan savannah, released flies from a petri dish and watched as the flies avoided the zebra pelt. Tombak, then a PhD candidate at Princeton, believes it’s an optical illusion—not one that works from far away, as some research has suggested, but up close. The stripes may create a sense of movement and speed that disorients the flies, she said.

“This work has given me a much greater appreciation for biting flies as an evolutionary force,” Tombak told Wired. “As a field ecologist, you get reminded of every time you go into the field—it really sucks to be bitten, they really drive you crazy. But when you’re an animal and you’re outside all the time and you don’t have the protections in the shelter that we do, it really does affect you.”

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