Wandering Glider Migrations
The greatest traveller of the insect world is the Wandering Glider dragonfly. In a year, these dragonflies make a multigenerational migration of 18,000 kilometres, with a single individual flying 6000 kilometres! They breed along the way. Their flight, aided by seasonal winds, spans many continents. They journey over high mountains and open oceans. In fact, they have even been seen crossing the Himalayas, making them some of the highest flying dragonflies in the world! This insect is barely five centimetres long.
Male adults are reddish in colour, and females are golden brown. Just like any other dragonfly, the Wandering Glider begins its life underwater – as a nymph. Lakes, wetlands, ponds, and paddy fields are important habitats for nymphs. They hatch from eggs and grow underwater, before climbing out, shedding their old skin, and turning into winged-adults. Their wings are special – they have a large surface area, which enables the insects to use the wind to carry them. They stroke their wings a few times and then glide for long periods, using little energy.
Wandering gliders are found on all continents except Antarctica.
It is believed that they fly from East Africa, across the Arabian Sea and come to India with the arriving monsoon.
They ride on the monsoon winds, which bring rain throughout the country. They are weather-tellers for farmers. For centuries, farmers have known that large congregations of these dragonflies in the skies are a sign of good rains that season, and hence a good harvest. What’s more, both nymphs and adult dragonflies feed on a range of crop pests – moths, mosquitoes, bugs, butterflies, and several other insects.
This insect is known by many names - wandering glider, globe skimmer, globe wanderer... In Japan, its name means "yellow dragonfly with delicate wings" whereas, in China, its name means “typhoon fly”, because it is often found in large numbers before a storm. In Malayalam it is called Thula Thumbi, as the insects begin to gather in South India in the Malayalam month of Thula (Sept 22 - Oct 22). The Pan Pantala Track is a citizen science project started by Odonate Society of India to track the great migration of the Wandering gliders, by crowd-sourcing observations made by people from India and abroad.
Water pollution, pesticide use and construction on water bodies and wetlands are some of the threats faced by these world-wandering insects.