Conventional wisdom says a zebra's black-and-white stripes camouflage the animal in tall grass—the better to evade the colorblind lion. But a new study says the pattern scrambles the vision of a tinier biter: the bloodsucking horsefly.
Coloured images revealed how light was polarised as it bounced off a zebra's coat
"We created an experimental set-up where we painted the different patterns onto boards," Dr Akesson told BBC Nature. She and her colleagues placed a blackboard, a whiteboard, and several boards with stripes of varying widths into one of the fields of a horse farm in rural Hungary."We put insect glue on the boards and counted the number of flies that each one attracted," she explained.The striped board that was the closest match to the actual pattern of a zebra's coat attracted by far the fewest flies, "even less than the white boards that were reflecting unpolarised light," Dr Akesson said."That was a surprise because, in a striped pattern, you still have these dark areas that are reflecting horizontally polarised light."But the narrower (and more zebra-like) the stripes, the less attractive they were to the flies." To test horseflies' reaction to a more realistic 3-D target, the team put four life-size "sticky horse models " into the field - one brown, one black, one white and one black-and-white striped, like a zebra. The researchers collected the trapped flies every two days, and found that the zebra-striped horse model attracted the fewest.