"This indicates that stripes may disrupt the flies" abilities to have a controlled landing'.
Scientists have been asking why zebras have stripes for over 150 years.
Theories about their function have included camouflage, a means of confusing predators, a method of signalling other zebras, and a system of heat control. However, the only explanation that has stood up to experimental verification suggests that the stripes serve to deter insects, which can sometimes carry deadly diseases. While there was no difference in the rate at which the flies landed on the horses' exposed heads, they touched and landed on the zebra coat far less often than either the black or white garment.
Striped patterns seem to work for humans as well, explaining why tribes from Africa, Australia, and southeast Asia have historical bodypainting traditions.
Researchers may have finally discovered why zebras have stripes, with new experiments showing that horse flies find it more hard to land on zebras than they do on uniformly coloured horses. But the flies managed to land on zebras less than a quarter as often. In a new study, researchers at the University of California Davis performed a series of experiments that investigated how stripes altered the behavior of biting insects.
An unusual experiment dressed horses up in stripy coats in the fields of Somerset to conduct the research.
In 2014, researchers showed the ranges of the horsefly and tsetse fly species and the three most distinctively striped equid species (Equus burchelli, E. zebra, and E. grevyi) overlap to a remarkable degree.
The researchers now think the stripes dazzle the flies so they can't land properly. Typically they came in too fast, often crashing into their prey or aborting the landing altogether. "Consequently, far fewer successful landings were experienced by zebras compared to horses", said Professor Tim Caro, Honorary Research Fellow from the University of Bristol's School of Biological Studies. Other limitations included that the path of the flies could only be seen in two dimensions from video recordings and that the horse coats were made of different materials, the United Kingdom media outlet Guardian reported.
As additional protection, zebras swish their tails nearly continuously to keep flies off, the study found. The striped animals nearly continuously swish their tails during the day and will stop feeding if they feel bothered.