Japanese Scientists Paint Cattle with Zebra-Like Stripes to Deter Biting Flies

Japanese scientists painted Japanese Black cattle with zebra-like stripes to examine whether this visual pattern could deter biting flies. The striped animals recorded roughly half as many fly landings as unpainted cattle, supporting the idea that zebra colouring acts as a natural defence against insects.

How was the experiment with the cattle carried out?

The research involved six Japanese Black cattle. Every animal underwent three separate conditions: black-and-white stripes were applied, it was painted with black stripes only, or it was left unpainted. This approach enabled the team to establish whether the result was caused by visual contrast rather than simply by paint being placed on the coat.

• The stripes measured about four to five centimetres wide;
• They were painted by hand using a water-based product;
• Each animal underwent all three treatments;
• Researchers photographed the animals’ bodies and legs;
• Flies that had landed were counted from the photographs;
• Movements used to repel insects were also recorded.

What happened to the cattle painted like zebras?

Cattle bearing black-and-white stripes attracted nearly 50% fewer flies than both unpainted animals and those painted with black stripes alone. Since no meaningful difference was found between the latter two groups, the researchers determined that neither the smell of the paint nor its application alone accounted for the outcome.

The experiment involving cattle painted like zebras also recorded fewer head, ear, leg and tail movements intended to drive insects away. Altogether, these defensive behaviours fell by around 20% in the striped animals.

Why do stripes make it harder for flies to land?

The exact mechanism has not yet been fully established. One leading explanation is that the contrast between light and dark bands disrupts flies’ visual perception as they approach, making it more difficult for them to regulate speed and land steadily on the animal.

• Flies rely on shine, movement and contrast to find hosts;
• Narrow bands may change the light reflected from a surface;
• The pattern may confuse the systems that guide their approach;
• Insects still approach the animal, but fail to land more often;
• Uniform black or white surfaces generally receive more landings.

Does the finding explain why zebras evolved stripes?

The experiment adds weight to protection from biting flies as one of the best-supported explanations for the evolution of stripes. Previous research had already found that insects land less often on striped surfaces and on horses covered with fabrics designed to mimic zebra patterns.

That does not mean that one study involving six cattle has completely settled the evolutionary debate. Explanations including camouflage, predator confusion and temperature control have received less support across different studies, although stripes may have more than one effect on an animal even if only one was decisive in their evolution.

Could painting cattle replace insecticides?

The researchers viewed the method as a potential alternative for reducing cattle exposure to flies and improving animal welfare. Fewer bites could mean fewer disruptions to feeding and resting, as well as less energy spent shaking the head, stamping the legs and swishing the tail.

Practical use still presents limitations. The paint used in the experiment faded within a few days, whereas the fly season can last for several months. Larger studies must assess safety, cost and durability before the stripes can be regarded as a visual repellent capable of replacing conventional methods on farms.