Termites are social insects often associated with towering earthen structures. While some species construct massive, intricate mounds, the architecture of termite nests is remarkably varied and highly adapted to specific environments. Termite housing ranges from complex external castles to diffuse networks hidden within soil or wood. The structures they build, whether visible or concealed, are sophisticated engineering feats designed for colony survival.
The Great Divide: Mound-Building vs. Non-Mound Species
The termite world is divided into species that build large, free-standing structures and those that do not. Mound-building termites, such as Macrotermes in Africa and Amitermes in Australia, create the colossal, visible nests most people recognize. These species are concentrated in tropical and subtropical savannas where their large colonies thrive. Their monumental nests are constructed from a cement-like mixture of soil particles, saliva, and excreta, designed for durability in harsh climates.
Conversely, many termite species, including subterranean and drywood groups, live without constructing a visible mound. Subterranean termites (Rhinotermitidae) establish their main nests below ground or within wood in contact with the soil. Drywood termites (Kalotermitidae) live entirely within the wood they consume. The choice of nesting location is directly tied to the species’ physiological needs and local environment.
Architectural Marvels: The Purpose of Termite Mounds
For the species that do build them, the mound functions as a highly specialized, self-regulating biostructure. A primary function is sophisticated thermoregulation, maintaining a stable internal temperature, often around 30°C, necessary for the colony’s metabolism and survival. The structure’s complex internal network of tunnels and shafts facilitates the circulation of air, helping to mitigate external temperature fluctuations.
The porous outer walls allow for necessary gas exchange between the interior and the atmosphere. This ventilation is important because the intense metabolic activity of the massive colony, along with its fungal gardens, produces significant heat and carbon dioxide. The mound structure actively manages this gas exchange, sometimes using diurnal temperature oscillations to drive convective air currents, effectively ventilating the nest.
For many African and Asian mound-builders, the structure supports their symbiotic relationship with fungal species of the genus Termitomyces. These termites are fungus farmers, cultivating fungal combs within specialized chambers. The mound maintains the high humidity and low carbon dioxide concentrations required for optimal fungal growth, which the termites rely on to break down indigestible cellulose. The mound’s dense construction provides defense against predators and protection from environmental threats like flooding.
Beyond the Mound: Alternative Termite Habitats
Species that do not build external mounds employ nesting strategies that integrate their homes into the surrounding environment. Subterranean termites, which are common across many regions, establish their primary nests in the soil, often many feet below the surface, where moisture levels are consistently high. They construct extensive, diffused gallery systems underground that can connect to multiple foraging sites.
To access food sources above ground while maintaining their crucial connection to the soil’s moisture, subterranean species build characteristic earthen tubes, often called shelter tubes. These runways, made of soil and termite secretions, serve as protected highways that shield the workers from desiccation, light, and predators as they forage. The subterranean nest itself is a network of chambers and tunnels within the earth or in wood buried in damp soil, rather than a single, external structure.
Drywood termites, in contrast, are “one-piece nesters” that live entirely within the wood they consume, such as structural timber, utility poles, or dead tree limbs. These species have a lower moisture requirement and do not need any contact with the soil, eliminating the need for external tubes or subterranean galleries. Their colonies are typically smaller than those of subterranean species. Their nesting chambers are the erratic galleries and tunnels they excavate within the wood, often distinguished by the presence of small, six-sided fecal pellets, known as frass, which they push out of “kick-holes”.