With dazzling blue iridescent wings, male morpho dragonflies should be hard to miss, but their wings are simultaneously capable of both spectacle and stealth. When viewed against a shining, watery background, the insects can vanish.
Male morpho dragonflies (Zenithoptera lanei), native to Central and northern South America, have wings that generate intense colour by using special, layered structures that alter how light reflects off their surface. The male dragonflies use their wings in flickering courtship displays to attract females and deter rival males.
at the University of SĂŁo Paulo in Brazil and his colleagues wondered if the dragonflies could also use their iridescence as camouflage.
Advertisement
Cezário and his colleagues collected 10 male morpho dragonflies in São Paulo state. In the lab, the researchers measured the light wavelengths reflected off the wings. They combined this with models of vision in birds and flies – the dragonflies’ predators and prey – as well as other male dragonflies that compete for mates. These models account for an animal’s ability to see fine details at a distance.
Based on the wings’ hue and colour intensity, the team found that other dragonflies, prey insects and birds could probably spot the structures against vegetation backgrounds. But the wings’ brightness matched that of the surface of water, providing “counter-brightness” camouflage. This means the dragonflies would blend in with a pond, say, if they were viewed from above by wary prey, hungry predators or aggressive competitors.
The researchers contend that this is the first known case of an insect using brightness matching as camouflage against the surface of water.
“In the day-to-day lives of the males, this camouflage effect is particularly important,” says Cezário, since their conspicuous positioning during dominance or courtship displays makes them vulnerable.
at the University of Bristol in the UK thinks that other animals may use iridescence for both display and self-preservation. “It is possible that iridescence can serve dual protective functions,” says Kjernsmo, whose team described an ’s own disappearing act in 2020. Iridescence might act as a bright warning signal to predators up close, but it conceals when further away.
The next step, says Cezário, is to see how well the brightness matching protects the dragonflies out in nature.
Journal of Zoology
Sign up for Wild Wild Life, a free monthly newsletter celebrating the diversity and science of animals, plants and Earth’s other weird and wonderful inhabitants
