Researchers at England’s University of Exeter and University of Essex found that butterfly wing patterns can create misleading motion signals during flight. Their study, published in Nature, suggests these illusions may help butterflies escape predators.
Contrasting markings work with wingbeats to distort the apparent direction of movement. Stripes produced particularly strong effects.
To test the idea, researchers combined high-speed footage of butterflies with computer modelling, simulated evolution and touchscreen experiments.
They recruited 100 human volunteers for 3,000 virtual butterfly-catching trials. Participants watched moving butterflies and tried to catch them by tapping a screen.
However, patterns predicted to cause greater visual confusion made people aim farther behind their targets.
Professor Jolyon Troscianko of the University of Exeter, a study leader, explained that wing movement changes how predators see a stripe.
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It can remain visible during the downward stroke but quickly fold away during the upward stroke. As a result, a butterfly flying upwards may appear to move downwards.
“Stripes are particularly good at interfering with the circuits that detect motion,” Troscianko told Reuters. Yet the team did not test attacks involving live birds and butterflies.
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Troscianko described those experiments as likely impractical and unethical. Instead, researchers hope that similarities in vertebrate motion-processing systems allow the findings to apply across species.
Brown or red butterflies typically caused less motion confusion. Troscianko suggested they may rely more on camouflage or warning colours.
Meanwhile, faster-seeing predators such as dragonflies and robber flies may respond differently. Troscianko said the illusions might not work against them.
