Scientists painted black cows with white stripes to test whether zebra markings deter biting flies

Theory Briefing

• Researchers in central Japan painted white stripes on black cows to mimic zebra markings and count biting fly landings.
• The experiment tests whether stripes evolved not for camouflage or temperature control, but to confuse and deter insects.
• Zebra stripes have puzzled biologists for decades — this cow-painting approach offers a low-tech way to isolate the fly-deterrence variable.
• If stripes reduce fly landings on cows, it strengthens the case that an ancient insect pressure shaped one of nature's most iconic patterns.