Every October, something extraordinary happens in the Maldives. Millions of dragonflies begin appearing across the islands, even though there is hardly any freshwater for them to breed in.
Where are they coming from?
Scientists believe many of these tiny travellers arrive from India, crossing hundreds of kilometres of open sea. Some may even continue their journey towards Africa.
And here’s what makes this so fascinating.
The globe skimmer dragonfly (Pantala flavescens), also called the wandering glider, measures barely five centimetres and weighs around 300 milligrams. That’s less than a gram!
Yet this tiny insect may undertake one of the most remarkable journeys in the animal world, travelling thousands of kilometres with help from something familiar to all of us in India: the monsoon.
But how does an insect so small cross an ocean without stopping? And why would it attempt such a journey in the first place?
Scientists have spent years trying to answer these questions.
The mystery of millions of dragonflies arriving in the Maldives
In 2009, researcher R Charles Anderson published a study about something that had puzzled observers in the Maldives for years.
Every October, enormous numbers of dragonflies appeared on the islands. But the Maldives has very little surface freshwater, making it an unlikely place for dragonflies to complete their life cycle.
By studying when the insects appeared in India and the Maldives, Anderson found evidence suggesting they were travelling from southern India, covering approximately 500 to 1,000 kilometres.
His findings, published in the Journal of Tropical Ecology, raised an even bigger possibility.
What if the Maldives was simply one stop on a much longer journey towards East Africa?
The answer appeared to be connected to the changing monsoon.
It all begins with something as simple as a rain-filled puddle
To understand why these dragonflies travel, we first need to understand where they raise their young.
Many dragonflies lay their eggs in ponds and lakes. The globe skimmer has an unusual advantage: it can breed in temporary pools formed by rainfall.
Think of the shallow puddles that appear in fields, open grounds and low-lying areas during India’s monsoon.
For this dragonfly, these pools can become nurseries.
The female lays her eggs in the water, where the young dragonflies develop before emerging as adults.
But these pools do not last forever. Once the rains stop, they begin drying up.
So, as rainfall shifts from one region to another, the dragonflies move towards places where fresh water becomes available.
India’s southwest monsoon, which generally lasts from June to September, creates ideal breeding opportunities.
And when the rains begin moving southwards, the dragonflies appear to follow.
Measuring around five centimetres and weighing less than a gram, it is among the world’s most widely distributed dragonflies. Photograph: (Bangalore Mirror)
How can something weighing less than a gram fly across an ocean?
Here’s where the story becomes even more remarkable.
If a dragonfly tried to cross the Indian Ocean by constantly beating its wings, it would soon run out of energy.
So how does it manage?
It may be doing something similar to what birds do: using favourable winds to help carry it forward.
Anderson’s research suggested that the insects travel with winds associated with a shifting band of clouds and rainfall near the equator.
Scientists call this the Inter-Tropical Convergence Zone, or ITCZ.
Simply put, it is a region where winds meet, creating changing weather patterns. As this region moves southwards after India’s monsoon, it can bring winds that favour the dragonflies’ journey.
Anderson suggested that they may fly more than 1,000 metres above the ground, where helpful winds could carry them towards the Maldives.
But there was still one important question.
Could their tiny bodies survive such a long flight?
In 2021, an international team of researchers led by Johanna S U Hedlund studied how much energy these dragonflies would need to cross the ocean.
Using computer models, they found that the insects could save enormous amounts of energy by gliding through the air and flapping their wings only when necessary.
According to their calculations, a dragonfly using a combination of gliding and wing-flapping could potentially remain airborne for around 230 hours under favourable assumptions.
By comparison, continuously flapping its wings would exhaust its estimated energy reserves in roughly four hours.
The research showed why the right winds could make such an extraordinary crossing possible.
However, these figures come from computer models. Scientists have yet to directly track individual globe skimmers throughout the proposed ocean journey.
From India to Africa, but the same dragonfly doesn’t make the whole trip
The Maldives may be only one part of the story.
In 2023, researchers from IIT Kharagpur, including Sanat Ranjan Kumar, Amit A Pawar, Arnab Roy and Sandeep Saha, examined how winds and rainfall could connect the dragonflies’ movements across the Indian Ocean.
Their research suggested a possible migration route:
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October to December: Dragonflies leave India and travel towards the Maldives as seasonal winds change.
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January to March: Favourable winds and rainfall may help them move towards the Seychelles and mainland Africa.
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May to July: Strong winds over the western Indian Ocean, known as the Somali Jet, may help later generations travel from Africa towards India.
Some dragonflies may breed in temporary rainwater pools along the way, including on islands where suitable conditions exist.
And here is an important detail.
The dragonfly that leaves India is not necessarily the one that returns.
The journey is believed to unfold across several generations. One generation travels, reproduces where conditions allow, and its offspring continue the movement.
Researchers estimate that four to five generations may be involved over a year, with young dragonflies emerging approximately 45 to 60 days after breeding.
The Wandering Glider (#Pantala flavescens), or Globe Skimmer, is a #dragonfly species known as the world’s longest distance #insect traveller, aptly named based on its migrating behaviour. #AareyForest #aareycolony #Aarey #SGNP #Odonata #saveaareyforest #Biodiversity #Mumbai https://t.co/Txu3Z7PdU0
— Rajesh Sanap (@RajeshVS87) August 24, 2022
A remarkable journey that still holds mysteries
Scientists have pieced together this possible migration by studying dragonfly sightings, rainfall, wind patterns and the energy needed for flight.
While the arrival of globe skimmers in the Maldives is well documented, much of the proposed journey between India and Africa remains a scientific hypothesis supported by modelling and observations.
There is still plenty to discover about the exact routes they take, where they breed and how they choose the winds that carry them.
But the research already gives us a fascinating way to look at something as familiar as the monsoon.
The same seasonal rains that fill our ponds, fields and lakes may also help make an extraordinary journey possible for an insect small enough to rest on our fingertip.
And the next time you spot a dragonfly after the rains, consider this: a creature that looks so delicate may be capable of travelling farther than we could ever imagine.
