Painting cows with zebra stripes cuts insect attacks

Stripped Cows-Optimized

Instead of using pesticides, painting cows with zebra-like stripes led to 50% reduction in the number of biting flies. As a result, cows painted with white stripes showed 20% reduction in fly-repelling behaviour.

Painting cows with zebra-like stripes may be a simple strategy to keep biting flies at bay. There was over 50% reduction in the number of biting flies seen on legs and body of the cows painted with zebra-like stripes compared with cows that were not painted thus. As a result of reduced biting fly attacks, the cows painted with white stripes showed 20% reduction in fly-repelling behaviour — foot stamping, tail flicking, skin twitching and head throwing. The results were published in the journal PLOS ONE.

Traditionally, pesticides have been used to control biting flies. Very often insects develop resistance against even newly introduced pesticides. In light of this, the environmental-friendly approach to control biting insects becomes appealing.

Several studies carried out earlier have shown that biting flies affect the behaviour of cattle. These flies can reduce grazing, feeding, and bedding down time of cattle and increase the fly-repelling behaviours of cows.

Japanese researchers painted six Japanese black cows with white stripes to resemble the zebra-like pattern. They used two control groups — black cows painted with black stripes and cow that were not painted with any stripes. All three cows were kept side-by-side and tied to a stake in the ground. They observed each cow in the morning and evening with a total of six observations for each cow. All the three cows were observed simultaneously in sunlight or shade during each observation and photo images were taken.

Painting is generally a short-term measure. “The development of more effective techniques to ensure the persistence of black-and-white stripes on livestock during the biting fly season (three-four months) may be necessary in order to apply this method to animal production sites,” they write.

Studies carried out earlier by painting inanimate objects with zebra-like stripes and covering horses with cloth coats with a striped pattern led to far fewer landings of flies.

Earlier studies by several researchers have attributed reduced landing of biting flies to modulation brightness or polarised light. Others have found insects approaching the target faster and failing to decelerate just before making contact with zebra surfaces. The stripes confuse the flies and as result they are unable to control their approach and landing.

Published in The Hindu on December 21, 2019