The Termite

Oct 12, 2008 Features / Columnists, Interesting Creatures in Guyana

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Well known for its wood-eating habits, the termite is part of a group of social insects that are usually classified as the taxonomic rank of the order Isoptera.

As social animals, they are termed eusocial along with the ants and some bees and wasps, which are all placed in the separate order Hymenoptera.

Termites mostly feed on dead plant material generally in the form of wood, leaf litter, soil or animal dung and about 10 per cent of the estimated 4,000 species are economically significant as pests that can cause serious structural damage to buildings, crops or plantation forests.

Their wood-eating habits see them sometimes doing great damage to unprotected buildings and other wooden structures.

Their habit of remaining concealed often results in their presence being undetected until the timbers are severely damaged and exhibit surface changes.

Once termites have entered a building, they do not limit themselves to wood since they also damage paper, cloth, carpets and other cellulosic materials.

But in order to resist the attacks of this ant species, one could avoid contact of susceptible timber with ground by using termite-resistant concrete, steel, or masonry foundation with appropriate barriers.

Even so, termites are able to bridge these with shelter tubes, and it has been known for termites to chew through piping made of soft plastics and even some metals, such as lead, to exploit moisture.

In general, new buildings should be constructed with embedded physical termite barriers so that there are no easy means for termites to gain concealed entry.

While barriers of poisoned soil, so called termite pre-treatment, have been in general use since the 1970s, it is preferable that these be used only for existing buildings without effective physical barriers.

The intent of termite barriers (whether physical, poisoned soil, or some of the new poisoned plastics) is to prevent the termites from gaining unseen access to structures.

In most instances, termites attempting to enter a barriered building will be forced into the less favourable approach of building shelter tubes up the outside walls, and thus, they can be clearly visible both to the building occupants and a range of predators.

It is, however, likely that termites could avoid this counter act, since they usually back away from exposure to unfavourable environmental conditions. They tend to remain hidden in tunnels in earth and wood.

Where they need to cross an impervious or unfavourable substrate, they cover their tracks with tubing made of faeces, plant matter, and soil. Sometimes these shelter tubes will extend for many metres, such as up the outside of a tree reaching from the soil to dead branches.

Termite barrier systems used for protecting buildings aim to prevent concealed termite access, thus forcing the termites out into the open where they must form clearly visible shelter tubes to gain entry.

However, as eusocial insects, termites live in colonies that, at maturity, number from several hundred to several million individuals.

They build nests to house their colonies and are commonly located in larger timber or in the soil in locations such as growing trees, inside fallen trees, underground, and in above-ground mounds which they construct, commonly called ‘anthills’ in some countries, despite the technical incorrectness of that name.

Mounds occur when the nest grows beyond its initially concealing surface. In tropical savannahs the mounds may be very large, with an extreme of nine metres (30 ft) high.

Two to three metres, however, would be typical for the largest mounds in most savannas. The shape ranges from somewhat amorphous domes or cones usually covered in grass or woody shrubs, to sculptured hard earth mounds, or a mixture of the two.

Despite the irregular mound shapes, the different species in an area can usually be identified by simply looking at the mounds.

Termites are a prime example of decentralised, self-organised systems using swarm intelligence and use this cooperation to exploit food sources and environments that could not be available to any single insect acting alone.

A typical colony contains nymphs (semi-mature young), workers, soldiers, and reproductive individuals of both genders, sometimes containing several egg-laying queens.

A female that has flown, mated and is producing eggs, is called a ‘queen’. Similarly, a male that has flown, mated, and remains in proximity to a queen, is termed a ‘king’.

Worker termites undertake the labours of foraging, food storage, brood, nest maintenance, and some of the defence effort in certain species. Workers are the main caste in the colony for the digestion of cellulose in food and are the most likely to be found in infested wood.

The soldier caste has anatomical and behavioural specializations, providing strength and armour which are primarily useful against an attack.

The proportion of soldiers within a colony varies both within and among species. Many soldiers have jaws so enlarged that they cannot feed themselves, but instead, like juveniles, are fed by workers.

Termites are generally grouped according to their feeding behaviour. Thus, the commonly used general groupings are subterranean, soil-feeding, drywood, dampwood, and grass-eating. Of these, subterraneans and drywoods are primarily responsible for damage to human-made structures.

All termites eat cellulose in its various forms as plant fibre, which is a rich energy source (as demonstrated by the amount of energy released when wood is burned), but remains difficult to digest. They are also well known for eating smaller insects in a last resort environment.

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