I was witness to a termite swarming event recently, during one of my travels, and managed to record some footage of the swarming termites (also called alates), which you can see below. The termites started swarming right after dusk around 7:30 pm, and swamped all the lights in and outside the guest room where I was staying.
Termite swarmers consist of males and females and are the future kings and queens of new termite colonies. Their role is to fly out from their nest, and seek out an individual of the opposite gender, preferably from another nest to mate, and start a new colony.
What is interesting is the timing of the swarm. Synchronization of all the nests in the given area is crucial, to ensure that at least a few of the alates get to mate and establish new colonies, since the mortality rate is extremely high by default. All the nests in the given area will synchronize their flight release times with each other precisely. Now, how they manage to coordinate all this is still unknown, I believe.
Normally, you cannot predict a termite swarm, although there are a few clues. For example, short term changes in the weather. From my observation, a spate of dry weather followed by some rain, or a spell of rainy weather followed by a fairly dry, windless evening – can trigger a swarming event, especially noticeable after dark. If there is a sizeable number of reproductive nymphs that have already reached adulthood inside any of the nests, these adult alates would have been ready to fly when the right conditions are attained outside.
The swarming itself is typically short and intense, usually never lasting more than an hour (for many species). Most termite species will choose to release their alates at dusk or night to minimize predation by birds and other predators. Sources of light serve as gathering points for the alates and attracts them by the hundreds or even thousands. However, most will still fall prey to lizards or geckos, spiders, ants, or simply fall into puddles of water and drown. Many get their wings wet and damaged in bathrooms when they seek out the bathroom lights. And of course, many more are killed by humans wielding bug-spray.
Termites lack the energy to fly for long, so typically by about 40 minutes into the swarming, many individuals would already have alighted and the swarm would have mostly subsided by then. It is during this phase, that many of them do not survive. Only a small percentage get to pair up successfully with another partner, dodge the predators through chance, and go on to establish a new colony.