Invertebrates
Globe Skimmer
Pantala flavescens · also called globe skimmer, wandering glider, global wanderer
The globe skimmer is a plain golden dragonfly, and it is a champion traveller. It lives on every continent except Antarctica, turns up on ocean islands before any other insect, and undertakes the longest migration known in the insect world — a multi-generational relay that carries the species back and forth across the Indian Ocean on the monsoon winds.
Overview
The globe skimmer is found in warm regions worldwide, breeding wherever temporary standing water forms. It is about 4.5 cm long, golden-yellow, with unusually broad hindwings that make it a strong glider and soarer — far more so than most dragonflies. It hunts small flying insects on the wing.
The longest insect migration
Populations cross the western Indian Ocean between India and East Africa, staging through the Maldives, and the full annual circuit — completed by several generations in relay — runs to something like 14,000 to 18,000 km. The migration follows the rain, so each generation arrives where fresh temporary pools are forming, breeds, and its offspring move on.
One global population
Genetic studies find that globe skimmers around the world are essentially a single interbreeding population — they mix so thoroughly that there is little genetic difference between continents.
A fast larva
The larvae develop in as little as five to eight weeks in rain pools, puddles, tanks, and swimming pools, which is what lets the species exploit water that may last only weeks and colonise remote islands.
Status
The globe skimmer is Least Concern and often increasing, helped by its willingness to breed in artificial water. Its sudden arrival ahead of a rain front makes it, in some regions, a sign that rain is coming.
Globe Skimmer: common questions
How far does the globe skimmer actually migrate?
No single dragonfly flies the whole distance. The migration is a relay, in which successive generations each fly one leg. The best-studied route runs between the Indian subcontinent and eastern and southern Africa, with dragonflies crossing hundreds of kilometres of open ocean, including a stretch with no land at all, and using the Maldive Islands as a rest stop. Adding up the legs, the round trip is estimated at roughly 14,000 to 18,000 kilometres, which would be the longest regular migration of any insect and comparable, in total distance, to the migrations of some birds.
How can such a small insect cross an ocean?
Several features make it possible. The globe skimmer has broad hindwings and a light body, so it is an efficient glider and can stay aloft for long periods with little effort, especially if it climbs into a following wind. It migrates at altitude, sometimes a kilometre or more up, where steady winds can carry it along at speed, and it times its crossings to the monsoon, effectively hitching a ride on a predictable seasonal air current. It also does not need to feed constantly, drawing on fat reserves, and it can pick up small insects that are being carried on the same winds.
Why are globe skimmers found on isolated islands where nothing else has reached?
Because they are exceptional dispersers and can breed in almost any water. A migrating swarm blown off course may make landfall on a remote atoll, and if there is any standing water there, a puddle, a rock pool, a water tank, the dragonflies can lay eggs and produce a new generation within weeks. This combination of long-range flight and a fast, undemanding larva means the globe skimmer is often the first, and sometimes for a long time the only, dragonfly on newly formed or newly colonisable islands, from volcanic islets to atomic-test atolls.
Is the globe skimmer good or bad to have around?
Generally good, from a human point of view. Adults eat large numbers of small flying insects, including mosquitoes and midges, and the aquatic larvae eat mosquito larvae and other small invertebrates in the temporary pools where both develop. Because the globe skimmer will readily use artificial water bodies and can complete its life cycle quickly, it often turns up in gardens, farms, and around towns, providing a modest amount of natural pest control. It does not bite or sting people and is harmless to handle.