Zebras black and white striped color protect against horseflies.
There are many theories about the unusual black and white color of zebras, including camouflage, confusion of predators and thermoregulation. Perhaps all of them are correct in one way or another, but one rather unexpected fact made scientists consider a new theory. It has been experimentally proven that horseflies are much less likely to land on striped surfaces than just on white or black ones.
Scientists attribute this phenomenon to a failure in the insect's navigation system when trying to land on a striped surface. That is, the color itself does not scare away insects, but they experience difficulty when they approach the zebra right before landing.
It turns out that horseflies give cattle a lot of discomfort. In order to somehow hide from annoying insects, poor animals are forced to huddle in heaps, because of which they overheat, eat less and injure each other more. This brings losses to farmers, who, in turn, pollinate livestock with pesticides to fight insects, which is not only expensive but also harmful. This, in turn, forced inquisitive minds to check whether the color of the zebra would help other animals to protect themselves from annoying insects.
In an experiment, 9 cows were brought in, where they were first painted with merely black stripes and then finished with a complete black and white paint job like zebras. Insect bites were counted on cows over several days, which was done to see if special color made any difference.
The findings showed that black and white contrasting colors reduced bites from flies by a notable amount (about 50 percent less). It seemed improbable that the strong scent of paint would scare away insects, as all cows — those solely with black stripes and those without stripes — did not experience a drop in insect bites.
I never cease to be amazed at the ingenuity of zebras, these simple-looking animals are much smarter than we think ;)
Kojima T, Oishi K, Matsubara Y, Uchiyama Y, Fukushima Y, Aoki N, et al. (2019) Cows painted with zebra-like striping can avoid biting fly attack. PLoS ONE 14(10): e0223447. https://doi.org/10.1371/journal.pone.0223447