Termites are well known for their nest building activities, since they can be considered the premier architects in the animal kingdom. Nests can be above ground, on the ground, underground, or inside wood.
Besides nest construction, termites tunnel and burrow extensively, so they contribute a lot to soil aeration and fertilization. In the tropics, termites play a major role in this regard (besides that of earthworms and ants). Termite subterranean tunnels can extend dozens of meters.
If they cannot reach their food source, they usually construct a pavement or covered tunnel out of earth, wood, or their own excrement, in order to gain access to that food supply. Such covered shelter tubes are a common sight in tropical forests.
(Above) Termite shelter tube running up a tree.
(Above) Another termite earth covered runway up a small tree.
A piece of wood that is or has been eaten by termites will always reveal an intricate latticework of galleries, passageways, and tunnels, which in many species will often be paved over with earth by the worker termites, slowly replacing the wood that is being eaten. Once thoroughly consumed, the termites abandon the wood, leaving behind mostly their earthworks underneath the surface of the piece of wood or log that they were eating.
(Above) Termite galleries in a dead tree.
In the subfamily Macrotermitinae, the termites construct fungus gardens that look somewhat like beehive honeycombs inside their nests, which are either subterranean or inside mounds. These fungus gardens are all composed of wood and plant matter, upon which grows fungus of the genus Termitomyces that break down the lignin in wood. Different species construct different looking fungus combs.
(Above) A termite fungus comb (Macrotermes gilvus)
(Above) Close up of termite fungus comb (Microtermes). Notice the white fungal spore heads.
Many termite species of the subfamily Nasutitermitinae (like Lacessititermes) construct arboreal nests. Arboreal nests often have downward pointing spikes that help to drain off rainwater, or are globular (round) in shape. They are always small and lightweight, housing only small colonies. If the branch or tree collapses, the nest and colony usually dies as well. The walls are thin and comprise a mixture of excrement, wood, and earth, called carton nests. Removing a section of the wall reveals a very elaborate labyrinth within.
(Above) Arboreal termite nest of (most probably) Microcerotermes spp. Notice the downward spikes.
(Above) Globular arboreal termite nest. Possibly a nasute species.
There are also species that construct small epigeal pillar nests that are flask or cone shaped, normally by species from the Termitinae subfamily. These nests probably seem to mainly serve the purpose of ventilation, and not for housing the colony, as most of the time there are only a few termites inside them, with the bulk of the colony probably below ground level.
(Above) Pillar termite nest (Dicuspiditermes nemorosus).