Monday, August 19, 2013

In Praise of Pantala

A challenge to net, members of the genus Pantala are well-known long-distance travellers.  This is a specimen of Pantala flavescens, the Wandering Glider, taken at the small ephemeral pond at Pittsfield Preserve on Aug. 16. Supreme aerialists, these dragonflies seem to be able to hover effortlessly over a body of water, and then zoom off vertically in pursuit of a potential mate or to chase off a rival.  It's sort of like watching one of those fighter jets go from landing speed to vertical with afterburners, but with a LOT less sound and energy expended.  Due to their ability to take advantage of wind currents, their high wing area to body-mass ratio, and their ability to go from egg to adult in 3 months, these dragonflies are found all over the world.  It's a global species, with migratory flights reported from the Indian subcontinent to Africa, and of course, all over North America.  Sometimes we laugh at their miscues - such as an ovipositing female mistaking a shiny car hood for a pond, but the laugh is on us if we try to swing a net and capture one.
Small temporary ponds can often have a lot of small creatures in them, including larval fishes.  The rapid development of Pantala nymphs is dependent on having access to a good food source, and however many miscues the females may make, it's obvious that many of them are successful.
This world-wide distribution map from Discover Life obviously lacks ALL the collection localities, but you can see that is it a cosmopolitan species.  Our UMMZ collections has hundreds of specimens from all over the world.  Alas, except for the MI specimens, the rest are not cataloged.  You can read about the migratory flights of Wandering Gliders in the Indian Ocean here., and in Venezuela here. In Michigan, we have numerous sightings of Pantala flavescens all over the state.  It's the other species - Pantala hymenea - that we see much less often.   August and September are the months when we most often see swarms of Wandering Gliders -- as they complete their summer's life cycle and emerge from the ponds, they will become more numerous (especially this year, with adequate water all summer). Eventually, these amazing fliers will make their way south of the Great Lakes and down the Atlantic coast to new ponds and deposit their eggs and fly off to the next pond.  We will see some of their offspring next May/June as they return to the North. In Michigan, we have specimen vouchers for counties as shown at the left.  Undoubtedly, there are many sight records that are not indicated here.

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