How Termite Colonies Function
Termites don't live on their own. They infest your house in colonies, organized similarly to a bee hive or an ant's nest. That affects the way you have to try to deal with them, because it's not just a matter of killing a bunch of them. You have to kill off the colony for the infestation to end.

How is a colony organized?
Like other hive insects, termites can be classified by caste:

Queens - There is a primary queen, which is usually the first termite that founded the colony, along with several other secondary queens that also lay eggs and will take over if the primary queen is killed.

King - There is only one king - the male termite that mates with the queen to help found the colony. When the founding king dies, in some species a reproductive will grow into a replacement king.

Soldiers - Soldier termites defend the nest from intruders, usually other insects.

Workers - These termites stay inside the nest, building it, tending to eggs and larva, and gathering food. They are white and often die easily outside the tunnels they have built from exposure to sunlight.

Reproductives (also called Neotenics or Swarmers) - They the ones you most often see - they fly around in swarms attempting to start new nests. They can also become queens if needed. They will fly for short periods, shedding their wings when they have found a new home.

No earth-wood contact.
This is a special problem due to the building practices in Thailand. It is common practice to install ground-floor door-frames before the ground floor slab is poured, so that the bottom of the door-frames actually rest in the earth below the house. First remedy:  remove all ground floor door-frames, and completely fill in the holes in the slab which remain. Install new door-frames, in any material, including wood. If you use wood door frames, cut them up short and set them on concrete risers. Inspect the entire ground floor, inside and out, to see if there are any other potential sources of earth-wood contact.

Water-pipes and drains
Another common building practice is to brick-in pipe and drain causeways. Even if the floor of these causeways is cement, there cannot be a good seal between PVC pipe and cement. Termites will find a way through the space and set up 'termite-tubes' and gain access to the entire building. A yearly inspection is recommended.

Wooden skirts
Remove all ground-floor wooden skirts and replace with the fake versions or with ceramic tile properly installed (no voids behind the tile). The way tiles are installed in Thailand leaves voids that the termites will use to crawl behind the tile to get to any wood in the area.

Ceilings
Open and inspect all suspended ceilings. Make an inspection hole in each room. Remove all the consumable materials.
Once you cut off the termites in the house from their ground access, they will die in about 2 months.

Dampwood Termite
Dampwood termites will often be seen swarming during the late spring and on into the early winter, depending upon the species. Despite the name, they will attack any wood, although they prefer wood that has been subject to moisture and decay, especially if there is no contact with the ground. Some will even form colonies in trees. Dampwood termites often work their way upward from ground level, eventually reaching the roof rafters. There are only two castes--soldiers and reproductives, the work of the colony is actually done by the nymphs. A colony may have up to 4,000 individuals.

Subterranean Termite
As their name implies, these termites live underground. These are the termites that probably cause the most overall damage to structures. Workers and soldiers are about 1/4th inch in size, while the reproductive males and females are about 3/8ths inch. Soldiers have a larger head with long mandibles. The reproductives are dark brown, while the workers are a colorless gray. Workers will eat any damp wood, and even damp carpets, to feed the other members of the colony. Even the nymphs will chew on wood. They have a high humidity requirement, and form tubes extending from the ground to travel in search of wood. The tubes are formed from saliva, soil, and bits of chewed wood. Tubes may also be used as shelter, migratory paths, and an exit for swarmers. Extreme damage usually takes years to develop, and the interior of wood is eaten leaving behind the outer shell, and any harder wood portions the termites didn’t want to finish.

Drywood Termite

The Drywood termite looks just like the Subterranean termite, except that has shorter legs and moves slowly, and it is more of a reddish brown color. Infestations of Drywood termites are just about as damaging as Subterranean termites.Drywood termites will excavate large pockets in the wood that they attack. They require no soil contact, and they can even infest dead limbs on trees. Drywood termites do require a source of moisture. They are usually noticed from the piles of fecal pellets that they eject from their kick-out holes. The pellets accumulate below these holes.

Formosean Termite
Some people call it the “super termite” because it has extremely large colonies and can do major amounts of damage in a relatively short period of time. There can be up to eight million Formosan Termites in a single colony—much larger than any other termite colony. The tunnels and tubes will branch out up to 75 meter in every direction, searching for wood to devour. They will eat anything containing cellulose—plants, lumber and wood products, cardboard and paper, etc. They have been known to chew through foam, some thin metals, plaster, and even asphalt to reach food.
Formosan Termites look just like any other subterranean termite, with the exception of the soldiers. They have a large, dark mandible (jaw) which can cross and form an “x”. Despite their fierce appearance, their bite is harmless to humans. A colony of Formosan Termites will contain a larger number of soldiers than other types of termites. They must be located near a source of moisture—plumbing or roof leaks, watered plants and landscaping, air conditioning condensation, areas where puddles form, etc. They can be located in attics, walls, trees, or even underground.