Outback Termites

Outback Termites are Everywhere – and they are very cool

I have read that there are 400 pounds of termites in the world for every human being. I can’t say that the ratio remains constant as human numbers increase and appropriate habitat for termites decreases; but it is an eye-opening number isn’t it? I think there are certainly 400 pounds of termites for every Australian. Here are a few images and descriptions from the Top End of the Northern Territory, south of Darwin. Termites are easy to find most everywhere but here in the warmth of north-central Australia they are impossible to miss. Many nest in the trees and other totally underground. In northern Australia there are many types that build mounds as they excavate their living quarters.

It is amazing to stand next to one of these mounds and think what went in to building it. There are no excavators, shovels, bull-dozers, concrete-mixers, or architectural plans; only a million tiny, soft, dark-loving social insects, apparently without language – and they are rarely visible. In the same area you mind find what are called Harvester Ants, actually a termite also, which has an underground colony with no mound and no chimney. I have wondered what they do with the material they excavate as I have rarely even seen a raised flat collar around their hole. It is often a bare area covered with discarded pieces of vegetation, but no dirt pile.
There are two kinds of termite that make these very large mounds; the genus’ Nasutitermes and Amitermes. I’d like to use cute and catchy common names but there are none; no one gives termite species personal (or even nick-) names. As a matter of fact there are about 2,600 species of termite in the world, 350 in Australia, and of the 350 there are at least 90 that have not even been identified, described, and given scientific binomial names.
The above image is from a cemetery near Pine Creek. The termite mounds often rise more than ten feet (3+ meters) and many are 20 feet (6+ meters) in circumference. Fran is standing next to the mound on the left side of the picture.
Termites tend to be homebodies. They are not very hardy and try to stay under cover in a steady environment. The mounds of most species are actually heating and cooling devices. The termites tend to live in the ground in a rather dense colony and the chimneys or mounds help air to flow from the warm moist aggregation of termites. In hot weather the air exhausts upward drawing cooler air from deep in the ground. The flow of air in many mounds is through a complex series of small channels in the mound. In most species soil structure and components and predominant weather regulate how deep the termites will dig. In really dry areas where there is no wet season they will excavate down to the water table. In areas with a wet season they usually build a mound they can live in when the area is flooded. In flooded areas there is a species (called magnetic termites, as the first thing determined was that the mounds were all aligned in the same compass direction) that cannot dig down due to the water and is subjected to significant temperature variations. So what does it do? It builds a thin, tombstone-like, mound that is oriented to gather morning sun, avoid mid-day sun, and be warmed again at sunset. They look like a series of large thin dominoes standing in a savannah, all oriented in the same direction.

The termites are really homebodies; they don’t go out in the light and even at night many species travel only in tunnels. The vertical brown line is a tunnel for a tree-dwelling termite to reach the ground to gather vegetation. There are a few species of mammals that will break open a trail and eat the frantic termites as they pass by or as they attempt to repair the break.

Different soils, different plants, different weather will all work to determine which type of termite predominates in specific areas. These Tumulitermes mounds are always dunce-cap like and always in what seem to be villages or clusters. They don’t get larger over time.

 The amount of work involved in building one of these larger mounds is mind-boggling. The interior contains a stuff called carton; a mix of vegetation, waste material, and (incidentally) clay. Carton is in just about all arboreal nests (tree types) and makes up some part of the innards of other mounds as well; looking like dried wet cardboard. In most cases it is dry and can be crushed by hand in other cases it is quite hard. The outer shell of the termite mound is almost always hard.

Culturally we think of termites as wood-eaters and especially as house-eaters. There are very few species that impact humans in such a manner. Termites do eat wood; their food stuff is that abundant, energy-rich but difficult to digest stuff called cellulose. The array of internal symbiotic protozoa and bacteria needed to digest cellulose makes the gut f a termite very impressive. In many ways a termite is a community of creatures rather than a single organism. The complex digestive process needed to “burn cellulose” most likely originated in ancestral cockroaches and has been modified by termites in various habitats. The image above shows the work of one of the tree-piping termites, probably Coptotermes. In the picture below a mound of Coptotermes sits adjacent to a eucalypt. It is thought that 70% of Australia’s trees have termite utilizing them. Aboriginal people used hollowed out stems for their woodwind instrument; the didgeridoo (didjeridu).

Termites are social; social insects. They are not closely related to ants but are related to the widespread and very successful cockroach line. The start off as eggs, then larva, and finally into one of three adult forms (worker, soldier, reproductive). Most colonies 90% workers and 10% soldiers. There may be millions of termites in a mound so the one reproductive female (and one male) doesn’t have any statistical position. She may live for 30 years or more and be the mother of tens of millions of workers and soldiers. As the rainy season approaches there will be a time when millions of hopeful females will leave the mound, rise into the sky, find a male, and (perhaps) start a new colony. The millions of termite females provide a huge surge in the food available to quolls, lizards, dragons, skinks, bandicoots, woodswallows, swifts, dollarbirds, and other inhabitants of the outback.

The soldier termites should get a bit of a mention. They are often small, delicate, and many types do not have fierce pinching mandibles. Many are specialists in chemical warfare. Some have poisons they squirt, others have sticky goo that immobilizes the predators, and other do carry a mean set of sharp, plier-like pincers. To a marauding ant the mincers must look like the horns of a Texas longhorn. As a matter of fact the predator that bothers termites the most are ants. Ants are also social insects but unlike termites they are agile, predaceous, and mobile during the day. In some cases colonies of ants will move into a termite mound or chimney.

The image below depicts one of the cathedral mound builders, probably one of the Nasutitermes. Like so many features of the Australian Outback the termite mounds were lovely, impressive, and other-worldly. In order to adapt to a challenging environment many creatures follow slowly along a successful lifestyle line. In the case of the termites they have adapted in many ways to the challenges of Outback living; enough so that they have become a major source of nutrients for all the other residents of the countryside. The Outback vertebrates are small and often dependent of the copious biomass of the termites.

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