Termites belong to an order of insects known as Isoptera which means ‘equal winged’. This refers to the winged alate caste that has two sets of wings which are front and rear that are equal in size. The word ‘termite’ is derived from the Latin word for woodworm. It is commonplace for termites to be described as white ants. This is a misnomer as ants and termites are clearly two very separate distinct castes of insects. In fact, termites are more closely related to cockroaches than ants whilst ants belong to an insect order known as hymenoptera that includes bees and wasps. The major distinctions between ants and termites relate to antennae, eyes, waist and abdomen. Ants generally have elbowed antennae, compound eyes and a waist between the thorax and the abdomen with the abdomen being pointed at the end. This is in stark contrast to termites that have antennae that look like a string of bead segments. Termites have no eyes, no waist and a blunt abdomen. The following captions of a termite and an ant below clearly demonstrate the variations described above.
Winged ants differ from winged termites which are known as alates and often referred to as winged reproductives.The wings on ants differ in shape and size with the front pair of wings being larger than the pair at the rear. The smaller rear wings also generally differ in shape from the front wings. All four wings on a termite alate are similar in both size and shape. However, alates do have a pair of compound eyes in common with the winged ant. Termites are generally white to light brown in colour with ants being brown, red or black and the termite workers and soldiers are sexless, wingless and blind. Termites also have fine cuticles that make them susceptible to desiccation when they are exposed to the elements or a dry environment. Ant workers and soldiers differ in that they are not sensitive to desiccation and can exist away from the humidity experienced inside their colony. The major similarities between ants and termites are that they have rigid caste systems, live in colonies and are insects. Ants are the natural enemy of termites. Termites travel in mud tunnels that are known as ‘leads’ or ‘galleries’ that conceal their movement and protects them from predators such as ants. These leads or galleries are constructed mainly from soil and their own excreted waste products.
There are over 2800 species of termites world wide, and more than 350 species of termites that have been recorded in Australia alone. Only about 30 of these Australian termite species actually damage timber timber-in-service, so it is obviously important to identify these particular termite species. Termites are nature’s recycler/decomposer and contribute by breaking down dead trees and grass into minerals and organic matter. They are also similar to earthworms as subterranean dwellers that tunnel through the top strata of soil and organic material. This aerates the soil and their excreta provides fertiliser and minerals that enriches the environment and assists with regrowth in areas that might otherwise be barren. Termite colonies are often used for this purpose when land, which has been used for mining, is being returned back to its original condition. Termites are an essential part and base element of the food chain with a wide variety of insects and animals, such as lizards, birds, echidnas and ants being dependent on termites as a ready supply of food. They are an extremely nutritious food source that provides sustenance to native wildlife. As can be readily noted from what has been discussed, termites form an important and integral function in the inter-relationship between flora and fauna and are an essential and necessary part of the chain of life in nature. Listed below under their separate family names are the major wood-feeding termite species found in Australia. They are as follows :
Coptotermes acinaciformis Coptotermes frenchi Coptotermes lacteus Coptotermes michaelseni Coptotermes raffrayi
Heterotermes ferox Heterotermes vagus Heterotermes validus Heterotermes venustus
Schedorhinotermes actuosus Schedorhinotermes breinli Schedorhinotermes intermedius
Microcerotermes serratus Microcerotermes turneri
Nasutitermes exitosus Nasutitermes fumigatus Nasutitermes graveolus Nasutitermes walkeri
The pictures of the termites of these varying species are all soldier caste individuals with heads and jaws designed for the defence of the colony. The soldier caste is the means by which a termite species can be identified with each soldier species exhibiting varying characteristics whereby they are able to be distinguished from other species. These are all subterranean termites that require some form of contact with the ground. The more commonly found termites are often referred to by pest managers as ‘mastos’, ‘coptos’ and ‘schedos’, which are respectively all abbreviations for mastotermes, coptotermes and schedorhinotermes species respectively. There is another family of termites which is not subterranean and does not require contact with the ground. These termites are most commonly found in sub-tropical or tropical areas and obtain their moisture from the timber that they feed from and inhabit. They have been found in areas in New South Wales and Queensland and appear to be spreading further afield. They are generally referred to as ‘drywood termites’ and listed below is the family name and the species found in Australia as follows :
Cryptotermes brevis Cryptotermes spp. Neotermes insularis
Cryptotermes brevis is an introduced pest, also known as the West Indian drywood termite, and government officials are on the lookout for any outbreaks of this destructive pest. Cryptotermes spp. is a native species to Australia whilst Neotermes insularis is often referred to as a ring-ant which is derived from its habit of working in the soft growth rings of living trees. These drywood termites differ from most of their subterranean relatives in that they have no actual worker caste. Treatment for drywood termite infestations in building requires tenting of the structure and the application of fumigant (Methyl Bromide) gas. ONLY borate treated timber is able to prevent an infestation of particularly destructive drywood termite species. In certain species of termites, nymphs perform the tasks that would normally be performed by workers and yet are still capable of developing into either soldiers or reproductives. This is similar to what occurs in the more primitive termite species – Mastotermes and Termopsidae. The fact that there are so many types of termites requires that identification of the species and the family be ascertained prior to treatment. Each termite family has separate and individual habits which involve different forms of treatment. Some termites may have a singular nest whilst others employ the use of several sub-nests that may even be built in the constructed walls of dwellings. A treatment that is successful in one instance may not be effective in the treatment of another species. Treatments will always involve the use of chemicals because chemicals are the only weapon man presently has to control termites. Unfortunately, chemicals are currently used for the purposes of treating infestations that have occurred rather than preventing the occurrence of infestations. The recent upsurge in the use of physical termite management systems clearly attests to these practices. The different castes of termites are all designed for a particular task or purpose relating primarily to the maintenance and/or survival of the colony. This co-operative caste arrangement is best described as a communion whereby everything becomes secondary to the survival of the colony. Termites will often cannibalise other members of their colony, or other colonies, in some instances. The king and queen start as alates that fly off from a parent colony to establish a new nest and propagate the species. Many thousands of alates set out on a flight and very few will survive to be able to reproduce. In Australia, alate flights usually occur in either the November-December or March-April time periods which avoid the outright summer heat. The best conditions for alate flights are generally before or after a storm when there are moderate temperatures and high humidity. These flights generally occur in the late afternoon so as to avoid the heat of the day. The high humidity means that the alates are unlikely to suffer desiccation which occurs in dry, hot conditions. The alates are darker in colour than other termites, have compound eyes and a stronger cuticle. The cuticle allows them to exist outside the humid nest conditions by making them less susceptible to desiccation.
The alate flight starts when they emerge from a purpose built slit in the mud nest or through slits made in either wood or bark. These slits are often referred to as ‘flight cuts’ and soldiers generally congregate around the opening so as to prevent entry to the nest by the natural enemies of termites. Alates most often will become the prey of birds, lizards, dragonflies, etc., and you will often see them attracted to a light source. If they do not find a mate and a suitable environment, they will die off without ever onwardly breeding and this is generally the fate of the vast majority of the alates. A pair of de-alates, which is a description of alates that have dropped their wings, will then proceed to start a nest generally in soil or decayed wood. The termite pairing will then excavate a chamber for the purposes of breeding and the queen will subsequently lay a small number of eggs. The de-alates are now the future king and queen of this new colony and are required to nurture their immediate offspring to establish the colony. The new nest may take 4-5 years before it matures into an established nest with several million occupants. The queen in a mature nest can generally lay about two thousand eggs per day, which translates into an extraordinary growth potential, and the offspring are generally cared for by the workers, or by nymphs in some species. Nymphs are similar to the workers in the more socially advanced species and occur in the more primitive species such as Termopsidae, Mastotermitidae and Kalotermitidae where no true worker caste exists. The nymphal stage provides versatility for more primitive termite species, with the developing nymphs able to become soldiers, reproductives or alates as well as being able to continue as a nymph with worker-like attributes. The less primitive species are more rigid in their caste system with distinct castes of soldiers, workers and reproductives being determined at an early stage of their nymphal development. It is important to note this major difference between termite species as it would obviously affect the means by which treatments are applied to various infestations. A termite king would typically have a similar life span to a queen and his job is to fertilise the queen, establish the colony and care for the initial offspring until nymphs or workers are produced to continue this role. It is common that some developing reproductives can become a supplementary king if the need arises and the king continues to fertilise the queen, when required, throughout his lifetime. A termite queen works with the king in establishing the new colony by reproducing and then tending to the initial offspring until nymph or workers are produced so as to continue this role. In most colonies, the queen becomes enlarged with a massive distended abdomen which is referred to as physogastry. The abdomen size and shape is created to accommodate the vast number of eggs that she produces, and whilst her head remains the same size, the rest of her body enlarges significantly. The termite queen can also create workers, nymphs, soldiers or alates dependent on the colony’s needs at the time. The initial termite queen retains the base of her wings after shedding occurs and is referred to as a macropterous queen. Often, the colonies will retain a number of neotenic queens which are supplementary queens for the purposes of reproduction. Neotonic queens do not go on a colonising flight and their purpose is to reproduce if the initial queen dies. They generally do not have the capacity to lay as many eggs as the initial queen and several neotenic queens may take over the reproduction duties of the queen. The worker forms the most numerous castes in the colony and is required to collect food, feed and nurture the young, feed the queen and the soldiers as well as building the nest and galleries for onward foraging expeditions.
A worker can be either a male or female with undeveloped reproductive organs and secondary sexual characteristics that do not develop. They are also blind as they do not have compound eyes attributed to alates. Workers have a fine cuticle which makes them transparent and their gut is generally darker in colour dependent on the food source that is passing through the gut. Workers are generally confined to the nest, galleries and sub-nest areas where a constant temperature is maintained along with high humidity. This is because they are very prone to desiccation because of their fine cuticle. Termites generally prefer softwoods to hardwoods with the exception of Nasutitermes which are generally timber pests of hardwood timber varieties. Soldiers are similar to workers in being both male and female with undeveloped reproductive organs and sexual characteristics that have not developed. The soldier heads are generally larger and darker than those of workers and the means by which we identify termite species. Soldiers’ heads have either a snout with mouthparts (Nasute) or well developed jaws (Mandibulate) dependent on the species. Some species have two different sized soldiers referred to as major and minor according to their size and the larger (major) soldiers and smaller (minor) soldiers both appear in the more established colonies, whilst often only minor soldiers will appear in small developing colonies. Examples of this occurrence can be readily noted in the termite species Schedorhinotermes intermedius. A soldier’s main task is to defend the colony against invaders such as insects and particularly ants. Some termite species soldiers have the ability to release white sticky fluids from their forehead which ensnare or blind their enemies. The soldier castes that defend the colony are generally unable to feed themselves and are fed by the workers or nymphs. Termites communicate with pheromones in the grooming process and pass information with these chemical messages. Reproductives are the sexual forms of termites that go through various growth stages and moults before becoming a fully formed adult. These stages include developing wing buds and establishing wings.
The reproductives shed their cuticles at the end of a growth (instar) stage and their hardened (sclerotised) cuticle has more chitin than other termites so as to assist them in coping with conditions outside the nest. Some reproductives may stay in the nest as neotenic queens in case the original queen dies so as to be able to continue her reproductive work. The nymph is a form that generally exists in the more primitive families of termites that have no true worker caste. These include the families of kalotermitidae, mastotermitidae and termopsidae. The nymph is a very versatile form that can develop into any termite caste dependent on the moult process. Nymphs can perform all the functions of a worker, moult to a pre-soldier (pseudergate) stage and then become a soldier, moult to become a reproductive nymph and onwardly become an alate or stay as a reproductive within the colony. Nymphs are clearly able to diversify into a form that best suits the needs of their colony. A subterranean termite colony will either nest in trees, underground or in mounds built on the ground dependent upon the termite species. Some termite species will adapt to their local circumstances so as to live in trees or on the ground dependent on the local conditions.
Coptotermes acinaciformis, the most widely distributed and probably the major problem termite in Australia, will generally nest underground in a subterranean nest in the more southern areas of Australia where they experience a cooler climate. In the northern areas where a warmer climate is experienced, this same species will generally build a mound to nest. It is common for termite species such as Nasutitermes walkeri to build a nest up in a tree (arboreal nest) which generally have a means of access to a cavity inside the tree. It is also common for kingfishers to build their own nest into the mudded tree nest of the termites thereby providing a constant temperature through a naturally insulated shelter, and also a plentiful source of food (termites) for their young hatchlings.
Some termites such as Microcerotermes turneri will actually build a nest on the top of a fence posts (pole nest) or a telegraph pole. Their nest is small and round and is adaptive so as to also be found in trees as well as on the ground. Several species are adapted to a subterranean nest which may be located at the base or in the root crown of a tree or a tree stump. These species include Coptotermes acinaciformis, Coptotermes frenchi and Schedorhinotermes intermedius. The location and type of nest is generally determined by the availability of food and water sources. The Kalotermitidae family generally nest in decayed or dead wood in logs and trees. The exception is Cryptotermes brevis known as the ‘drywood termite’ which is able to inhabit timber in buildings providing there is reasonable moisture content therein. Their ability to survive in small colonies and to exist without ground contact and minimal moisture makes them a formidable pest. They are found where there is humidity present and can inhabit furniture as well as house timbers. It is not uncommon for termites to nest in or under buildings providing they have access to a moisture source and people in high rises thirty floors above the ground have noted the effects of termites. What is interesting to note is that the variances between the different species will determine either what methodology is adopted in providing a treatment where damage or infestation has occurred or otherwise provide the best means of averting a termite infestation. In Australia, there are generally one or two termite nests within 50 metres of a family home and this means that the home is therefore within comfortable foraging distance of the nest. Again, it is extremely important to identify the species of termites that exist in your area and in your yard. A large mound nearby might belong to a grass eating species and may require no treatment at all. What must be recognised by homeowners are the following pertinent facts :
- Not all termites eat timber and termites serve a useful function in nature as a recycler of trees, grasses and other plants to provide nutrients that enrich the land.
- Termites are an integral, natural part of the environment and contribute immensely to the health and welfare of an ecosystem. They are essential in nature.
- Termites vary in habits and preferences from species to species requiring varying forms of approach and treatment to prevent infestation.
- Termite management procedures may vary dependent on factors such as construction type, soil conditions, identified species and access to the nest.
- A homeowner should not attempt to eradicate or apply any form of treatment to termites or their nest as this may adversely affect future treatments.
- Chemical termiticides required for the treatment of termite infestations are generally registered by the APVMA and are not available to the general public.
- Pest management is an extremely skilled profession that requires its practitioners to be capable of identifying species and applying appropriate management systems.