Possibly not everyone’s chosen topic but here’s a little bit of information about termite mounds

Termites have colonised pretty well all land masses on earth, other than Antarctica.  However, termite mounds are only found in any numbers in Australia, Africa and South America.  There are 360 known species of termites in Australia, compared with over 3,000 worldwide.  They are eusocial insects (which means the highest and most successful level of organisation of any social insect colony).  Each species builds a nest, and if that nest protrudes above the ground it is called a termite mound.

As we drove up through Western Australia and then across the top of Australia through the Northern Territory and Queensland, Sarah and I were staggered at the vast number of termite mounds, which often dominate the landscape in all directions.  I can’t find any reliable estimate of the number that are out there in the Australian outback, but it must run to many millions.  A single termite mound can be home to a colony of as few as several hundred termites, but more often up to many millions.

Although some of the mounds we’ve seen in Australia are large, especially in the Northern Territory where the largest of Australia’s termite mounds exist, being up to 3m or more in height, the majority of the mounds we’ve seen to date have been relatively modest in size, maybe waist high on average. Compare this with some of the mounds in Africa, which has the largest mounds in the world, reaching up to 8 or 9 metres.  The tallest mound ever recorded was in the DRC (Democratic Republic of Congo), standing at 12.8 metres.

Anyway, seeing all these mounds around Australia I decided to do a little bit of research, and this is a small part of what I’ve found.

It is a telling statistic that although termites and ants make up only 1% of insect species, they account for 50% of all insect biomass.  In other words, there are a lot of them around!  A termite queen is the longest lived of any insect and can reportedly live for 30-50 years, although more normally 15 years, laying hundreds of millions of eggs during that period (one every three seconds, or 30,000 per day!).  As a little aside, in case anyone is interested, termites originally evolved from cockroaches, albeit a very long time ago (170 million years).

As for a typical termite mound, about one third of the mound is above ground, with the remaining two thirds below ground. The principal purpose of the mound is usually described in the literature as being to provide a protective environment for the termite colony and to regulate airflow, temperature and humidity.  Delving a bit deeper and it appears that there is also a complicated symbiotic relationship going on at the very heart of a termite mound.  Underneath the queen’s chamber is a ‘fungus garden’ which can occupy as much as 8 times the space occupied by the termites.  The termite mound contains long foraging tunnels into the surrounding area, through which some of the termites exit and then return with their intestines stuffed full of chewed grass or wood.  Arriving back at the mound they ‘defecate’ this chewed fibre.  Other workers in the colony gather this product and construct combs (think honeycomb), which are then seeded with fungus spores.  As these fungus spores sprout and grow they dissolve the tough fibrous cellulose mixture left by the termites (a bit like an external stomach for the termites) leaving a relatively high energy mixture for the termites to then feed upon.  Good for the fungus and good for the termites.  It has been estimated (by some professor who’s devoted his life to this subject) that the fungus accounts for 85% of the metabolism taking place inside a mound.

There are other interesting aspects of some of these termite nests.  For instance, in the Northern Territory many of the termite mounds are oriented towards magnetic north, so that the base of a 3m high mound might be 3m wide in the north-south direction and perhaps 1.5m in the east-west direction, providing more warmth in the morning and evening, and less exposure in the extreme heat of the midday sun.  On the Mary River, again in the Northern Territory, we observed a number of termite nests high up in trees on the banks of the river.  Each nest was connected to the ground by a long tunnel covering the outside of the tree trunk, the point apparently being that when the area floods during the rainy season, the nest will remain above the water level.  I guess when you’ve been around for millions of years you get the hang of what works and what doesn’t.  Who would have thought that termites could be so fascinating.