The Macrotermes termites

The Macrotermes genus (subfamily Macrotermitinae) has some very interesting species of termites. They are the largest termite species of all, if you take into account the size of the queen, which can attain a length of nearly 6 inches (15 cm) in Macrotermes natalensis. There are about 330 species in the Macrotermes genus, spread out over tropical Africa and Asia.

Most species of Macrotermes build mounds, although there are a few subterranean species. The mounds vary in height from less than a foot to an incredible height of about 30 feet (9 meters), depending on the species. The biggest and tallest mounds are found in Africa and are constructed by mainly a few large species, notably M. falciger, M. bellicosus, M.natalensis, M.michaelseni, and M. subhyalinus. In South East Asia, the main species of mound building Macrotermes are M. gilvus and M. carbonarius. It should be noted that some other species of termites build mounds and Macrotermes are not an exception; however, they build the most spectacular mounds among termites.

The unique thing about Macrotermes termites is their fungus cultivation habit, which all of them do, and they have been doing that far longer than us humans have been cultivating crops – Millions of years! This is insect agriculture at its finest. The way they do it is to maintain a constant temperature range in their nests in the range of 29-32 degrees Celsius, in order to simulate the right conditions for their fungus gardens to grow.

The fungus grows from the chewed up pieces of wood and plant matter which the workers bring back from their foraging. This fungus is a specialized wood rot fungus of the genus Termitomyces, which is actually edible to humans and is considered a prized delicacy in tropical regions of the world when the fruiting bodies of the fungus grow out from the termite mounds or ground, sprouting out from within the termite nests.

When you consider that the dry harsh savannahs of Africa do not present a suitable habitat for this fungi to grow, and man has never quite succeeded in culturing this fungi, what the termites have been doing out in the parched savannahs is special. The huge mounds of Macrotermes termites are complex structures with their own ventilation, air ducts, heating and cooling systems, and chambers containing fungus gardens which the termites cultivate. Such a high degree of organized behavior and architectural evolution from such tiny, small insects is unrivalled in the entire animal kingdom – and perhaps even man.

Macrotermes mound

(Above) The structure of a typical Macrotermes spp mound

Macrotermes species are noted for having two sizes of workers and two sizes of solders (major and minor workers and soldiers). This is called polymorphism, or in this case, caste dimorphism. The colors of the soldier’s heads are usually orange or reddish brown. There is a black Macrotermes though – Macrotermes carbonarius, which is almost wholly jet black in color. Macrotermes are not found in the Americas but are common throughout most of Africa and tropical Asia.

Dimorphic soldier termites

(Above) Dimorphic soldiers in Macrotermes malaccensis.

Many Macrotermes species are generally not pests, but some may be agricultural or exotic tree plantation pests. Most of them are unable to survive in an urban environment or outside their natural habitat, and therefore won’t be a problem for most buildings and homes. In fact, it is a common sight in many rural areas of tropical regions to see multiple mounds in the compounds and gardens of homes (or along the roadsides), and not one single dwelling is bothered by them. However in Africa, Macrotermes has been a serious pest of some agricultural crops and tree plantations.

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