What is a termite swarm?

The really odd thing about a termite swarm is that it is the one time when cooperation goes out the window.  It is every termite for his- or herself.

A swarm is a coordinated flight of winged (alate) termites.  It happens several times a year when the local colonies try to release fully grown (fit, healthy, strong, winged and sighted) termites capable of reproduction.  They fly off, typically only a 100 m (say 300 feet) or so unless there's a breeze.  The aim, if female, is to quickly find a home site and if male, to pair with a female who's found  a good home site.

They sometimes seem to fill the sky.  Almost all fail but just enough make it so that they keep on surviving.  Flights are short, termites only get into one flight.  It is all or nothing.  There's no going back into the nest. 

More here.