Termites are insects that belong to the order Blattodea. The word “termite” derives from the Latin “termes” (which means “woodworm” or “white ant”) and “terere” (which means “to rub”, “to wear”, “to erode”). Early on, they were known as “terminarium” or “termitaria”, while, in early English, they were simply referred to as “wood ants” or “white ants”. Despite this reference, though, it is important to acknowledge that termites are not, in fact, ants. There are around 3,100 species of termites currently recognized.
Description and distribution
Termites’ appearance will vary according to the species, as well as the caste, they form part of. All termites present one pair of antennae. These fulfil various functions, including sensing smell (including pheromones), taste, and touch (including heat and vibration), and are made out of 3 segments:
- a scape;
- a pedicel (which is typically shorter than the scape);
- and a flagellum.
A termite’s face also presents a clypeus, which is divided into a postclypeus and anteclypeus. The mouthparts contain a maxillae and a labium, both of which have palps that help termites sense and handle food, and a set of mandibles. Most termites also present a set of eyes, although most workers and soldiers are blind. Some species have lateral ocelli, while others do not.
A termite’s thorax presents 3 segments:
- the prothorax;
- the mesothorax;
- and the metathorax.
One pair of legs is attached to each of these segments, and 2 pairs of wings to the mesothorax and the metathorax. As opposed to ants, the hindwings and the forewings of termites are equal in length. When the termite is at rest, its wings are carried parallel to the body, while when the termite is in flight, they will be carried at a right angle. Most termites, however, are poor flyers, the general technique being to launch themselves into the air and fly in a random direction. As a result, they only fly for brief periods of time, relying mostly on their legs to move around. Note that only the reproductive caste of termites has wings; workers and soldiers do not.
The abdomen is divided into 10 segments, with 2 plates: the tergites (the dorsal portion) and the sternites (the ventral portion). The abdomen also presents the reproductive organs, which are similar to those of cockroaches, but overall more simplified.
In the case of “soldiers” (the non-reproductive castes of termites), the appearance changes. They are wingless, with movement relying exclusively on the 6 legs, which are larger and heavier than those of the reproductive specimens. In some species, “soldiers” do not have eyes, and are therefore completely blind. In others, they have compound eyes, which are used in orientation and in distinguishing sunlight from moonlight.
Termites are generally small insects, of around 4-15mm in length. The largest termites, however, are the queens of the species Macrotermes bellicosus, measuring over 10cm in length.
Termites are among the most successful groups of insects on Earth, present on all continents, with the exception of Antarctica. The distribution across these landmasses, however, varies, with the diversity of species being low in Europe (10 known species) and North America (50 known species), but very high in South America (over 400 known species), Asia (around 400 known species) and Africa (over 1,000 known species).
Diversity and behaviour
There are 3 ecological groups of termites:
- dampwood, found in coniferous forests;
- drywood, found in hardwood forests and living in the wood that they consume;
- and subterranean, found in various areas and living in the soil.
Having soft cuticles, termites are unable to inhabit cold or even cool environments. Instead, they enjoy humidity, requiring a source of moisture in order to survive. Places where you can find termites include: soil, dead logs, tree stumps, dry wood structures, etc. Most species of termites live in nests, which can be made out of a variety of materials (most commonly faeces, but also partly digested plant material, soil, or mud), and which fulfil the primary function of sheltering termites against predators and against unfavourable environmental conditions, such as excessive rain or excessive sunlight.
Termites live in colonies, whose sizes can range from a couple of hundred individuals, to several million individuals. Termites are eusocial in nature. “Eusocial” is a term that refers to the highest level of organization of animal sociality. As such, just as bees and wasps, termites:
- divide labour between reproductive and non-reproductive groups: all colonies have fertile males (which are called “kings”) and one or more fertile females (which are called “queens”), as well as sterile males and females (which are called “workers” or “soldiers”);
- take care of younglings cooperatively: the young termites are not cared for specifically by their parents, but by the entire colony;
- have overlapping generations within a colony of adults.
This eusociality is one of the reasons why researchers refer to termite colonies as “superorganisms”: because they are almost self-regulating entities in themselves, all the individuals exhibiting some sort of collective cognition. A colony of termites is therefore divided into a so-called caste system, made out of:
- the King;
- the Queen;
- the secondary Queen;
- the tertiary Queen;
- and workers.
Workers carry out most of the labour. They are charged with finding and storing food, as well as with maintaining the nest in top condition. They are also charged with digesting the cellulose in the food and with feeding their reproductive nest-mates. This process is referred to as trophallaxis, an effective nutritional tactic that converts and recycles nitrogenous components, and it is also the technique that frees the parents from feeding all but the first generation of offspring. Not all species have a so-called “workers caste”; some rely on the nymphs to perform this work.
Soldiers have anatomical and behavioural specialization, which allow them to fulfil their sole purpose: that of defending the colony. They have large heads and jaws, very powerful and so enlarged that they are unable to feed themselves. Instead, like younglings, they are fed by workers. In defending the colony, soldiers can employ a wide variety of strategies. Some use their bodies (primarily their heads) to block tunnels, in an effort to prevent enemies from entering the nest. In cases where the breach is larger than the soldier’s head, they will use their bodies to form special formations to protect again the enemy. Soldiers from some species are able to exude noxious liquids through a horn-like projection, while others commit suicide by autothysis: rupturing a large gland, which secretes a yellow fluid that becomes sticky on contact with air, catching the enemy that is trying to invade the nest (in the case of insects).
Breeding and dietary information
The reproductive caste is comprised mainly of a fertile male and female, known as the king and the queen. The two mate for life and are responsible for egg production for the entire colony. In some species, the abdomen of the queen can swell up dramatically in order to increase fertility, a characteristic known as physogastrism. This can cause free movement to be greatly reduced, in which case the queen is assisted by workers. If the queen dies, the king has the ability to produce pheromones which will encourage the development of replacement termite queens, namely the secondary and tertiary queens. These are “supplementary reproductives”; they go through an incomplete metamorphosis on the path to becoming alates, only maturing in the case in which the primary queen dies.
As opposed to ants, which undergo a complete metamorphosis, termites only undergo an incomplete metamorphosis: egg, nymph, and adult. Nymphs resemble small adults, and grow through a series of moults; in most species, 3 moults are required to reach adulthood, a process which can last months, depending mostly on environmental conditions, such as food availability and temperature.
The first “stage” of adulthood is that of workers. Some specimens then further moult into soldiers or into alates. As mentioned briefly before, pheromones regulate the caste system, preventing all but a couple of termites from becoming fertile females. Alates only leave the colony when a nuptial flight occurs. The timing of the nuptial flight depends on the species, as well as on environmental conditions, such as time of the day, moisture, wind speed, precipitation, etc. In some species, the alates emerge during summer, while in others, during winter; some emerge during the day, others only at sunset. Regardless of the timing, though, the process is largely the same. During the nuptial flight, males and females pair up and fly away in search of a suitable place to form a new colony. They will not mate until they have found such a place. Once they have, though, they excavate a chamber big enough for both, close up the entrance, and mate. Following mating, they will spend the rest of their lives in that nest.
In the very early stages of the colony, the female will lay 10-20 eggs at a time. When the colony is several years old, though, she can lay as many as 1,000 a day, seeing as a queen’s capacity to lay eggs increases with age. In some species, the mature queen has such a distended abdomen that she is capable of laying as many as 40,000 eggs a day.
Communication between termites occurs in a variety of situations, such as building nests, foraging, and locating and fighting enemies. Because most species are blind, they use mechanical, chemical, and pheromonal cues to recognize and understand each other. 3 main pheromones are emitted:
- alarm pheromones, which are secreted from the frontal gland;
- trail pheromones, which are secreted from the sternal gland;
- sex pheromones, which are secreted from the sternal and tergal glands.
To exemplify how this communication occurs: workers will leave pheromones on the trails they travel to reach sources of food, so that other members of the colony can detect them through olfactory receptors and follow them.
Among the reproductive caste, secondary and tertiary queens may compete with one another, in the case that the primary queen dies. In some cases, competition between colonies may also occur, resulting in agonistic behaviour. This, in turn, can lead to fights, to mortality on both sides, and even to losses (or gains) or territory. Interestingly, in some species, “cemetery pits” emerge, where the bodies of dead termites (mostly soldiers) will be buried. Competition — and conflict — can also occur between termites and ants, also due to matters regarding territory.
There are a variety of predators that feed on termites, including bats, bears, bees, various species of birds, centipedes, chimpanzees, cockroaches, crickets, dragonflies, foxes, frogs, lizards, mice, scorpions, sloth bears, spiders, toads, wasps, and many others. Some animals, such as spiders from the family Ammoxenidae or aardwolfs (Proteles cristata), are specialist termite predators, which means that they feed solely on termites. By far, however, the greatest enemies of termites are ants.
Termites are also susceptible to infection by a wide variety of parasites, although much less so than bees, wasps, and ants. Some of these parasites include dipteran flies, different species of mites (e.g. Pyemotes), different kinds of nematode parasites (e.g. the order Rhabditida), as well as viruses (e.g. Entomopoxvirinae or the Nuclear Polyhedrosis Virus). Moreover, some fungi pathogens (e.g. Aspergillus nomius), not host-specific in nature, are easily transmitted through direct physical contact, and are therefore very threatening to the entire colony. The danger is considered to be great enough that, if threatened with infection by such a parasite, an entire colony may relocate.
Termite queens have the longest lifespan of any insect in the world, with some living up to 50 years.
When it comes to their dietary needs, it is known that termites are detritivores, obtaining nutrients by consuming detritus: dead plant and animal material at any level of decomposition. More specifically, they feed on leaves, soil, roots, humus, animal feces, etc. Many species also feed on cellulose, which they retrieve from wood, having a specialized midgut that is capable of breaking down the fibre. Because wood is, even so, difficult to digest, many termites prefer to consume fungus-infected wood, with the added benefit that fungi are high in protein.
According to their feeding habits, termites can therefore be placed into 2 groups: the lower termites, which feed predominantly on wood; and the higher termites, which feed on a wider variety of materials.
Some species (such as Gnathamitermes tubiformans) have seasonal food habits, consuming different foods, in different quantities, during the summer as opposed to spring and autumn. Different species of termites also have different preferences when it comes to the type of wood they consume. These are believed to be based on factors such as hardness, moisture content, as well as resin and lignin content, but they can also be a result of conditioned or learned behaviour.
The way termites obtain food also differs from species to species. Some feed on the same wood structures that they inhabit, others procure the food from locations close to the nest. Others, still, have complicated foraging mechanisms. The species Nasutitermes costalis, for instance, has a 3-staged foraging technique. First of all, soldiers will scout the area; once they find a food source, they communicate with others, calling more soldiers to the area in question. Secondly, workers will start to appear, until, finally, soldiers retreat, leaving the area in the hands of many workers.
Termites as pests
Out of all the pests that infest homes, ranging from other species of insects to different species of rodents, termites are considered to be the most dangerous, because they are the only ones that can actually single-handedly destroy the foundation of a house in only a handful of short years. Not only that, but no house is safe from termites. All of them provide, in some measure or another, the food that termites thrive on: cellulose-based material. Whether it is your house that is built out of wood, or you simply have a library with a large number of old books, termites will find a way to reach the food they need.
Several hundred species of termites are pests that are also economically significant. They not only cause serious damage to buildings, but destroy crops or plantation forests. The West Indian drywood termite (Cryptotermes brevis), for example, is regarded as such an invasive species.
Out of the 3,100-recognized species of termites, 183 can cause damage to wood structures, and out of those, 83 can cause significant damage in a relatively short period of time. More specifically, the number of species that are considered to be pests are:
- in North America: 9;
- in Central America and the West Indies: 17;
- in tropical Africa: 24;
- in the Indian subcontinent: 26;
- in Australia: 16.
In the southwestern United States only, the damage caused by termites is considered to be of approximately $1,5 billion each year. The cost of the damage worldwide is impossible to be determined. On the other hand, termites are of considerable ecological importance, seeing as they recycle wood and plant matter. Whether you want to prevent an infestation with them, or are already dealing with an infestation and want to eliminate termites from your property, check our related articles which talk about way in which you can ‘Prevent infestation with Termites’ and also ‘How to get rid of Termites’.