Northern Australia is a big country shaped by a small insect:
the termite. In many places the very look of northern savannas owes
much to the mounds built by colonies of this insect. North
Australian savannas have one of the most diverse range of termite
mounds in the world: from the enormous buttressed
“cathedrals” of spinifex termites, to the remarkably
aligned “magnetic” mounds and miniature cities of
columns built by various Amitermes species.
Mastotermes darwiniensis - one of many termite
species that have nests largely hidden from view underground or in
Even more termite species — around three-quarters of
those found in north Australia — are hidden from view,
building nests within trees or underground.
As far as we can tell, most of these termite species are only
found in Australia.
Despite being surrounded by termites our understanding of the
ecology of the different termite species remains limited. Although
many of us are warily familiar with a few timber-eating pest
species, most of the termite species of northern Australia, which
may feed on grass, wood or humus, are largely unstudied. However,
we can provide some answers to a few key questions.
Are termites the same as ants?
Termites are only distantly related to ants. Like the ants, bees
and wasps termites are social insects that live together in
well-organised colonies, however, unlike the other social insects
which are all closely related, termites have evolved from
cockroach-like ancestors and have independently evolved the social
way of living. Like the ants, the termite colony is made up of
different types of insects or “castes”: worker
termites, soldier termites and reproductive termites with
Close-up the worker termites, which comprise the majority of
termites in most colonies, generally look quite different from ants
— they have pale, soft bodies and are blind.
Termite workers (on the right) are usually a few
mm long. Ants are a diverse group of insects and some species have
very large workers such as this one from the genus Odontomachus on
These broad differences can be traced back to their distinct
ancestries. Ants, bees and wasps all undergo a dramatic change as
they grow, transforming from grub-like larvae into fully developed
adults via a pupal stage. Termites, like cockroaches, instead grow
gradually from juveniles, which look like small mature insects,
through a series of moults into progressively more developed forms
— either workers, soldiers or reproductives.
Are termites the same as cockroaches?
Recent research on the genetics of termites has suggested that
termites are so closely related to cockroaches that we should
consider them as an unusually specialized type of cockroach –
or in taxonomic terms they are more like a family within the larger
cockroach order (Blattodea) rather than an order in their own right
(Isoptera) (reference 1). However, whatever new insights are
gained into their relationship with other insects, we can still
happily distinguish termites from “other” cockroaches
as the common names are unlikely to change.
Of ‘white ants’ and
Termites in Australia are often referred to as ‘white
ants’. Of course they are not ants (see above) but this term
presumably came from the termites’ resemblance to ants
– like ants they are encountered as wingless insects in
groups but unlike ants, worker termites are often pale or even
white – hence the term ‘white ants’.
There is presumably a similar origin in the term
‘anthill’ for a termite mound. The association of
termite mounds with ants would have been helped by the fact that
ant colonies often invade termite mounds and many termite mounds
will have ants living inside some parts. In most cases if you
see ants living in a mound in northern Australia, it will be a
termite mound. Relatively few Australian ant species build above
ground mounds and they usually look quite different from termite
What do the different types of termites in a colony do?
If you could look inside a typical termite colony you would
probably see that most termites were rather similar with small,
pale bodies and no wings — these are the "worker" termites
that make up the bulk of the colony. Looking a bit longer might
then reveal a smaller group of termites with unusually shaped heads
with large jaws, or perhaps with heads drawn out into long snouts
for squirting chemicals — these are the colony's "soldier"
termites. Depending on the time of year, further examination might
then reveal termites with wings, either in buds or fully developed.
These are the reproductive termites, or winged "alates". These
different groups of termites are often called termite castes.
The reproductive termites develop in the way many other insects
do: they grow wings, fully developed eyes, reproductive organs and
a stiff, brownish skin. It is these alates which fly out from the
termite colony each year to look for a mate. If they are lucky they
and their mate will establish a colony and become the Queen and
King termites of the new colony. The great majority of alates,
however, does not survive the mating flight.
Winged termites or 'Alates' - are generally poor
fliers and few will survive a mating flight to become a Queen or
King termite (below)
A Queen termite (left) with an enlarged abodomen
for egg production and a King termite (right).
Most termites in the colony, however, never grow wings and never
become sexually mature but have an inhibited, skewed development in
which they acquire either strong jaws for foraging and mound
building as the worker caste (or worker-like caste in some groups)
— or acquire pincers or chemical weapons for defending the
colony as the soldier caste.
Different termite species can have their own
distinctive soldiers ranging from those with chemical defences (at
left) to those with different shaped jaws (at right).
Neither of these castes develops compound eyes, sexual organs or
fully pigmented skin and as result most residents of a termite
colony are blind, thin-skinned and susceptible to dehydration
— relative weaklings in the largely armoured and mobile
insect Class. For more information see Termite Colonies
Why do termites live in colonies?
It is thought that the social organization seen in these insects
offers a number of advantages — a key one being that a group
of insects working together can achieve feats that enhance their
survival that would be impossible for an individual insect. The
obvious example for termites is their remarkable ability to
cooperatively build well-insulated, often complex nests — and
networks of foraging tunnels that spread out from the nest to food
The large mounds constructed by magnetic
termites Amitermes meridionalis (at left in background) and
spinifex termites Nasutitermes triodiae (at right in
How long do termite colonies live?
We do know that the worker and soldier termites only live for a
few years, but as the members of a colony are being continually
renewed by new eggs from the queen, a colony can outlast individual
workers and soldiers. So can we age the termite mounds to get an
idea of how long the colony lasts? Unfortunately, unlike corals or
trees, termite mounds cannot be easily dated by looking at growth
rings. This is because in many colonies the termites are
continually re-working the inside of the mound. Individual mounds
have been observed to survive for decades.
The history of one cathedral mound provides interesting clues as
to the age of termites. When the Overland Telegraph line was being
constructed, the top of this presumably tall mound was removed in
1872 because it interfered with the wires. At that stage it must
have been already several decades old and, fifty years later, in
1935 it was still thriving. This colony may therefore have reached
an age of almost 100 years, before it fell into disuse, sometime
before the next inspection in the 1950s. Colonies belonging to this
type of termite the spinifex termite (Nasutitermes triodiae)
are believed to be derived from just one irreplaceable queen, the
mound lasting just as long as she does, in which case she would be
a very long-lived insect. However, we still know very little about
the biology of this species and it could be that replacement queens
are produced in these long-lasting colonies.
Researchers studying golden shouldered parrots reckon that that
conical mounds used by the birds must be 30 years old or more
before they are suitable for nest sites. They calculated a growth
rate of between one and two centimetres a year for these mounds,
some even decreasing in size.
How do termites establish new colonies?
The analogy of termite colonies with plants is also apt when it
comes to dispersal, as like many plants they reproduce by allowing
“seeds” to be dispersed — in this case the seeds
are the winged male and female alates which fly out from the nests
in coordinated swarms and then meet up after landing to try and
reproduce and found new colonies.
A termite colony will usually take a few months to produce
alates from larvae and in the tropical savannas, swarms of male and
female alates are often released from nests at the onset of the wet
season when the moist conditions are often suitable for starting a
new colony. Alates are generally poor fliers and do not travel very
far — understandable given that male and female
alates need to meet up and dispersal flights of more than a few
hundred metres reduce the likelihood of this happening. It may also
disadvantage a colony with significant genetic investment in
adaptations to a local environment to have long dispersal flights
that risk leaving that environment. For more information see
All about mounds
You can see hundreds of the mounds built by termite colonies in
some parts of the tropical savannas and it is easy to overlook the
amazing feat of cooperation they represent. For example, consider a
mature cathedral mound around 5m tall. Given it was built by
insects around 5mm long this is equivalent to humans getting
together and building a massive skyscraper over a kilometer high
and covering many city blocks.
Why do small animals appear to have super powers?
Termites can build towers a thousand times their own height,
ants can lift objects many times their own size – are these
“super” animals which through sheer luck happen to be
too small to threaten us? Not really – much of their apparent
"super" power stems from the very fact that they are so small
compared to us. As animals get larger their muscles get more
powerful but this occurs at a different rate to the way the objects
those muscles need to lift get heavier as they get larger.
If you double the length or width of a muscle then, very
roughly, the strength increases in proportion to the
cross-sectional area of the muscle, so a muscle twice as wide and
long could become four times as strong. But if you double the
linear dimensions of an object that muscle might lift, that object
becomes eight times as heavy, because you increase the
volume by a factor of eight in doubling the width, depth and
So a flea can jump hundreds of times its own height, but if it
was a hundred times larger - the size of a frog - its muscles might
be around 10,000 times stronger, but its body would be a million
times heavier .
For more information visit this part
of the Flying Turtle Science and Technology site.
Having mounds means these insects can survive harsh, dry
conditions in the humid micro-climates of their nests, a luxury
afforded to few other animals - a factor that may contribute to
termites’ remarkable abundance in the seasonally-dry tropics
But there are limits to what a termite colony can accomplish. It
appears it is more difficult to sustain suitable microclimates in
above-ground mounds in the dry and cool temperate regions and
consequently mound-building termite species are not particularly
diverse outside the tropics. However, those species that live in
hardier nests hollowed out in wood or under a protective layer of
soil can live in the warmer temperate regions of Australia as well
as the tropics.
How many different types of termites are there?
There are more than 2800 termite species in the world. This is
not many compared to the more than 11,000 different species of
ants, but quite a lot compared to the 280 or so different
marsupials. There are about 263 termite species found in Australia
and around 160 of these can be found in northern Australia
Although termites all look pretty similar to our eyes, and
although they are not as diverse as the ants, there is a marked
difference between many of the species. For example, one of the
smallest Australian species, Occultitermes occultus, has
soldiers a little over 2mm long — compare this to
Neotermes insularis soldiers with giant heads 7mm long and
15mm in length overall with large mandibles.
How abundant are termites?
While termites have a restricted distribution compared to the
other social insects (ants, bees and wasps are found throughout
tropical and temperate regions), what they lack in range they make
up for in numbers. Termites can be extremely abundant in the
tropical savannas and along with ants are the most abundant insects
found in savanna soils . Savanna habitat covered in the large nests
of spinifex termites, Nasutitermes triodiae, may support a
few hundred tonnes of termite per square kilometer – far
greater than the weight of cattle supported per square kilometre on
What do termites eat?
This abundance is no doubt partly due to the fact that termites
consume a widely available resource most other animals cannot
exploit: the cellulose and lignin that stiffen the woody parts of
plants. By virtue of symbiotic bacteria or protozoa in their gut,
termites can digest the cellulose and lignin present in a wide
range of wood and grass, living or dead, as well as the plant
material in litter and soil – with individual species
specializing on particular sources of cellulose.
For example over 80% of older eucalypt species were found to
have been piped by termites (most likely mostly Coptotermes
acinaciformis) in the woodlands in Kakadu National Park and
those of the Darwin area (references 3 and 4).
A log piped by termites.
Termites and Didjeridus
The Aboriginal wind instrument, the didjeridu, is made from
termite-hollowed trunks or branches of trees. In north-east Arnhem
Land, for example, the common eucalypt species E. tetrodonta
and E. miniata are used by the Yolgnu. While the termites do
the work of hollowing out the wood, considerable skill and
experience is required to select the tree and then prepare the
harvested wood to make a good didjeridu (reference 5). Commonly it
is the trunks of smaller trees that are selected and recent
research (reference 4) has suggested that because smaller
trees with very hollowed trunks are not likely to live very long
anyway, traditional harvesting of trees for didgeridus does not
have a great impact on tree populations. The same cannot be said
for non-traditional modern harvesting where often larger trees are
cut down and the branches harvested. The scale of non-traditional
harvesting is significant and the impact on tree populations has
yet to be quantified (reference 6).
Other species, such as the spinifex termites mentioned above,
specialize on grass and many of the abundant termite mounds in the
savannas are insect-crafted silos of chopped grass. There are also
groups that specialize on the plant material in soil and humus, and
groups that feed on the litter layer.
A mound of a nasute termite colony cut open to
reveal the stored chopped grass
Where do you find the different sorts of
The termites that build mounds are concentrated in
Australia’s tropical savannas while many tree- and
soil-dwelling species are found in both tropical and warm temperate
regions. It is likely that it is harder for termites to maintain a
warm, humid environment in an above-ground mound – which may
also need to have good ventilation for storing the grass the
termites eat – than it is for termites to maintain stable
conditions inside wood or under soil.
Relatively few species of termite are found in Australian
tropical rainforests or monsoon forest patches (reference 7). This
appears to have little to do with the rainforest environment itself
as similar habitats in South East Asia and South America can have
very high termite diversities. It may be a legacy of the fact that
when rainforests were initially established in Australia few
rainforest-adapted termites came with them.
Why are there different types of mounds and
Given that their nests and mounds appear to provide stable
internal conditions for termites in a wide range of environments it
is perhaps not surprising that many nests appear to be shaped to
suit those different environments. This is seen in Amitermes
laurenis: in well-drained habitats it builds small dome-shaped
mounds, yet in seasonally flooded flats it constructs huge mounds
aligned along a north-south axis, often hundreds of times larger.
Studies on this species and A. meridionalis, which also
builds oriented mounds, suggest that such mounds are an adaptation
to the seasonally waterlogged conditions: the high surface-area
shape oriented north-south creates a stable environment for living
above the ground in flooded habitats where migrating to an
underground refuge is impossible. Recent genetic studies imply this
behaviour may have evolved several times and more than once within
A. laurensis (references 8 and 9).
'Magnetic' termite mounds built by Amitermes
meridionalis appear to be adapted to seasonally flooded
Other savanna mound-builders such as the spinifex termite N.
triodiae also show great variation in mound type which may also
be related to local environmental conditions: mounds with higher
surface areas, which may facilitate better ventilation of stored
grass, being found in the northern, more humid locations. However,
this relationship has not been studied yet.
Two types of mound bult by Nasutitermes triodiae
- the tall, fluted "athedral" type found on the Top End of the NT
and the smaller, bulbous mound found further south in the Kimberley
There is no reason why we should not expect the nests built
within wood and under the soils to have a structure and shape that
is also adapted to local environmental conditions. In this way
termite colonies and their nests may be rather like plants, which
are also stuck in one spot, that have trunks, foliage and root
systems adapted to suit local conditions. For more information see
Variety of termite mounds
What impact do termites have on other plants and
Termites can occur in great numbers with millions of them in a
single colony and they also release their flying reproductives in
simultaneous flights from many colonies, so the result is often
thick swarms of alates that are a food bonanza for local animals
like ants, small mammals, birds, spiders, frogs and lizards.
These swarms are effectively a large aerial injection of
nutrients into the ecosytem – nutrients that have been
liberated from the cellulose in dead wood and grass. This
dead wood and grass is abundant in the dry season and were it not
for termites, many of the nutrients locked up in this plant
material would be dispersed by burning. Termite nests also house
these nutrients in the bodies of the termites and in the salivary
and fecal material in their walls and when the nests eventually
decompose they allow those precious nutrients to re-enter the
soil to be available for plant growth.
Termite colonies are one of the few
living things that can sustain this cycling process through the
northern dry season. While other decomposing organisms like
bacteria and fungi struggle in very dry environments, termites
function with year-round life-support from the humid nest. Not only
can they maintain their nutrient cycling, but through their
underground activity they also assist water penetration in soils.
Such insect-driven nutrient cycling may be more important in
Australia than it is in other tropical savannas like those of
Africa, where large herbivores are significant in nutrient cycling
(reference 10). For more information see Animals that Nest in Termite Mounds and Termite Predators
Termites and People
Despite their important role in
ecosystems, termites have unfortunately become victims of what
marketers call the Bad Apple Syndrome: the handful of species that
attack buildings and agriculture have sullied the reputation of
that great termite majority that pose no such threat. That early
European settlers had a more jaundiced view is hardly surprising:
reports tell of Mastotermes darwiniensis completely
destroying a homestead and its fences in 2-3 months (reference
Indigenous people of the tropical
savannas, however, have long recognized termites as useful: for
medicines, for dietary supplements, their carton for cooking, and
mounds for camp fires. Recently however, their profile in the
general community has changed in the north with large termite
mounds now seen as tourist draw cards and being featured in nature
documentaries. Termites are also being investigated as a possible
indicator species for monitoring soil condition.
Should we go a step further and be
concerned about threats to termites? Termites are not immune to
global changes in the environment and there is evidence, for
example, that vegetation thickening in Cape York Peninsula and the
Northern Territory may be having an adverse impact on populations
of “magnetic” mound-building Amitermes colonies.
Dead and dying nests of these slow-dispersing insect colonies that
build mounds oriented to the sun, have been observed apparently
trapped beneath a slowly increasing shade from canopy cover.
However even for these relatively well-known species we simply
don’t know enough about their ecology yet to make definitive
assessments of their conservation status.
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H.M., Watson, J.A.L., Balderson, J., Cassis, G. and New, T.R.
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Dermaptera, Phasmatodea, Embioptera, Zoraptera. CSIRO/ABRS
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Taylor R., Cloake J, and Forner J. (2002) Harvesting
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industry in the Northern Territory (ed. R. Taylor) pp.
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