The Formosan subterranean termite is an invasive, forign termite species. Compared to the native U.S. subterranean termite species they are more agressive, they forage in a wider area and they grow into much larger colonies of termites. While native termite colonies can grow to includes several hundred thousand members, mature Formosan termite colonies can surpass a million members.
Alates, commonly called termite swarmers, are wingged reproductive termites that leave the colony to start their own colonies. It’s common to see termites swarming on moist, spring nights just before dusk. They are attracted to light, and on those perfect spring nights its common to see them swarming around lights, windows and on window seals.
Due to their greater numbers, Formosan termite colonies can release a massive number of swarmers. While the alates tend to have a tiny chance of individual success, their shear numbers guarntee that new colonies will be started.
Studying Termite Swarming
To help study termites better, and to create semi-controlled enviroments, researchers and students will setup termite study areas. These areas are generally away some where the termites can be left alone without causing damage to peoples property. In these areas mock homes can be setup to moitor and track termites as they procede to demolish the wood.
In one such study area, while going out to study the termite swarming season, researchers found an old section of wood that had been completely infested by Formosan termites. The termites had eaten into the wood and part of the colony was now living there. Closer inspection revealed that that secion of the colony included a high concentration of Formosan termite alates.
They were able to relocate the wood to an enclosed environment, where they setup light traps to attract and trap the swarmers. Then they proceded to monitor the termites as their swarming began and ended. The main swarming happened during a 5 day period. Every day around dusk swarms of Formosan alates would emerge. The alates were collected and counted. In the 5 day period, an estimated 68,729 alates were collected (Su & Scheffrahn 1987). While this may have only represented a part of the total number of alates for the colony, the numbers are quite impresssive.
Day 1: 10,371
Day 2: 23,997
Day 3: 26,500
Day 4: 4, 768
Day 5: 3, 363
After the 5th day of the main swarming, there were small sporadic swarms of just a couple hundred alates for another 6 days (Su & Scheffrahn 1987).
Termite Swarm Survival Rates
It’s estimated that only 0.5% of the termite alates will survive to start a colony (Su & Scheffrahn 1987). That means, from a swarm of 68,000; only 300-400 are going to survive. Even then, the shear numbers show how its easy to get an idea as to why Formosan termites are able to spread so quilcky.
Nan-Yao Su and Rudolf H. Scheffrahn; Alate Production of a Field Colony of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae); Sociobiology Vol. 13, No. 3, 1987; Retrieved from http://flrec.ifas.ufl.edu/pdfs/Su_pub/Su017_Alate.pdf