We all know of birds migrating over thousands of kilometres, crossing oceans and mountains. The Wandering Glider is a dragonfly known as the world’s longest distance insect traveller.
The Wandering Glider ( Pantala flavescens ) is also called the Globe Skimmer or the Globe Wanderer named for its migrating behaviour. It belongs to the order Odonata literally meaning ‘the toothed one’, due to its serrated mandibles, which explains its predatory habits. Libellulidae, the family to which this dragonfly belongs, is the largest dragonfly family in the world, represented by over 1,000 species spread across the world. The Wandering Glider was first described in 1798 by Johan Christian Fabricius, a Danish zoologist specialising in insects and one of the most important entomologists of the 18th century.
This insect-helicoper looks delicate but is one of the most skilled aerial ambush predators of the insect kingdom, intercepting its prey mostly in mid-air using its feet. To avoid the prey escaping, it’ll rip the wings off mosquitoes, termites, beetles, even butterflies and sometimes off other dragonflies, suggesting borderline cannibalism.
A large adult dragonfly is capable of feeding on over 1,000 mosquitoes a day, making it a natural pest controller, giving commercial mosquito repellents a run for their money. With an increase in the use of insecticides and pesticides, the population of dragonflies has taken a hit, thereby making mosquito-infestation a problem.
Wandering Gliders grow up to 4.5-5 cm in length and have a three-segmented body: head, thorax and abdomen, with their wingspan ranging between 7 cm and 8.5 cm. Their wings are clear, almost transparent, and very broad at the base. The front of the head varies between yellow to red, with the thorax being yellow or golden with a dark line running through it.
With a nearly 360-degree vision, the head is all-eyes with two massive globular compound eyes, giving it extraordinary vision. Human eyes exhibit tri-chromatic vision where they see colours as a combination of red, blue and green, but dragonflies far surpass that colour spectrum of vision, studies across the world reveal.
Being the most widespread of all dragonflies in the world, the Wandering Glider is omnipresent in all continents except for Antarctica and is sparse in Europe. Considering its long-migrating behaviour, monitoring is difficult and thus their lifespan remains uncertain. In addition to being the insect that travels the longest distance, it is also the highest flying dragonfly, recorded at over 6,000 metres in the Himalayas.
After mating, the male and the female remain connected for a while, even while the females are ovipositing (laying eggs) a clutch of about 500-2,000 eggs in a variety of aquatic habitats like puddles, ponds, marshes, rivers, and swimming pools. Like adults, their larvae are voracious predators too, feeding actively on aquatic invertebrates like mosquito larvae, other aquatic insect larvae, tadpoles of frogs, and even on small fish in water.
Mostly seen before and after the monsoon season, the Wandering Glider is everywhere these days, in the morning and evening. Certain insectivorous (insect-eating) birds like Bee-eaters and Jacobin Cuckoos tend to follow these swarms for a feast, especially over fields, where they swarm. They also are a delicate part of the food web, where they feed on smaller insects but are eaten by birds, lizards, and frogs.
Considering their incredible vision and aerial prowess, they are an inspiration to several new technologies like visual systems and drones.
The writer is the founder of NINOX - Owl About Nature, a nature-awareness initiative. He is the Delhi-NCR reviewer for Ebird, a Cornell University initiative, monitoring rare sightings of birds. He formerly led a programme of WWF India.
