Most people equate the 'Mexican wave' with football, crowded stadiums and a good time. But the wave is not just for screaming fans. Researchers from the University of Graz in Austria and the Royal Botanic Gardens Kew in the UK have unlocked the mystery behind the phenomenon of 'shimmering' in giant honeybees. Their finding was recently published in the journal PLoS ONE. Hundreds or even thousands of individual honeybees flip their abdomens upwards creating a Mexican-wave-like pattern on the beehive when they are on the alert. The research team said this shimmering phenomenon allows the honeybees to communicate and defend themselves against predatory hornets. The move is significant particularly because the wave forces the predators to find other prey, thus protecting not only the honeybees but their nests as well. Professor Gerald Kastberger from the Institute of Zoology at the University of Graz led the team of scientists investigating how the shimmering behaviour actually works. Researchers have for quite some time understood that the shimmering was triggered by visual stimuli of predators. The giant honeybees kick-start their nest mates into action, thus creating the shimmering effect. The shimmering behaviour generates a 'bee curtain' or 'shelter zone' around the comb -around 50 cm- making communication between the bees fast, effective and continuous. More to the point, the potential predators hit a wall and fail to gain entry. Professor Kastberger installed two cameras to catch the activity of honeybee colonies. The research team evaluated some 500 episodes of interactions between honeybees and hornets, frame by frame. They showed that giant honeybee colonies spark off the shimmering behaviour in order to fend off the hornets; the faster the hornets approach, the stronger the shimmering from the bees. The study also showed that when faced with this iridescent Mexican wave, the hornets turned and buzzed off. According to the researchers, large-scale shimmering can fend off the predatory hornets, while small-scale shimmering successfully confuses the nasty pests. The predators are forced to forage for bees that fly freely. In their report, the researchers also focused on the evolutionary principles of how giant honeybees benefit from shimmering. Based on their results, the team said shimmering is a key factor in the lives of honeybees, particularly as it gives them the ability to maintain the open-nesting lifestyle they developed millions of years ago. It is the South-East Asian honeybees that form their single-comb nests out in the open. These giant honeybees opt for nests located on trees, rocks or human buildings. It is typical behaviour for them to revisit these sites over the years, the team said. According to the researchers, information transfer and self organisation are the key components behind the shimmering effect.