Termites are a type of insect that is crucial to the economy. Termites have both benefits and ill effects. In terms of benefits, termites are considered a vital part of the forest society. They are both creators and destroyers in an ecosystem. Termites produce bad effects because cellulose is their main nutrient . Cellulose is an important component of the wood. Hence, termites severely destroy wood or wooden structures in buildings as well as various materials, belongings, furnitures and tools made from wood and other goods with cellulose as their components. Microbes in intestines of termites digest cellulose as their food. There are more than 150 types of termites spreading around Thailand. However, just more than 10 types cause damages to domestic woods. The most damaging type of termites in Thailand is “Asian Subterranean Termite”. Termites of this type create their termitehills underground. They like high moisture but hate sunlight and good ventilation. Subterranean termites are considered the most critical to the economy because they cause damages to houses and buildings to the value of hundred millions of baht a year. The damage starts from termites living underground creating pathways up to the top through cracks in concrete floor or the joints between walls, pillars or ground beams. Then they destroy various wooden structures in the building such as wooden pillars and beams, parquet floor, ceilings, window and door frames. Apart from food, dampness is another important factor in their lives. This biological and ecological information of termites helps in terms of planning and laying measures to prevent and eradicate this type of termites efficiently. There are various methods for instance, creating toxic ground under the building, creating a preventive fence under the building so subterranean termites are unable to go through or making wood toxic so termites cannot use it as food. There are both chemical and non-chemical approaches. These measures to prevent and eradicate termites can be used by the general public to reduce damages and prolong the usefulness of wood.
General Biological and Ecological Features of Termites
Termites are social insects. They like to stay together in big groups in their hills. Generally, they do not like sunlight. They prefer dark and damp places. They start from tussock moths which are breeding termites. In the breeding season, each year during the transition between seasons, after a period of tussock moths flying around light sources, their wings will tire out and are torn. The moths will come down to the ground and leave their wings behind. Male moths will follow the scent of the female moths. They will go underground. Once they are bred, the couple will become the king and queen of termites. The queen termite is like a machine that produces eggs 24 hours a day. Their eggs are well treated and will grow to become caterpillars. The first generation of termite caterpillars will all grow to become workers to find food for the queen. Once the termites in that hill are fully grown, other castes of termites will emerge.
1. Workers- are small white termites without wings, genders and eyes.
They use their antenna to find the ways. They do almost all the work in the hills for instance looking for food to feed the queen, king, caterpillars and soldiers. Other castes of termites do not find their own food. Moreover, they also construct and clean their hills. They look after the eggs. They culture moulds and repair damaged hills. They also create paths to find food. The number of worker termites is more than 90% of the total termites in a hill.
2. Soldiers- are termites with huge heads with dark colours.
They are strong. Their notable quality lies in their huge molars that change into a plier-like organ with sharp edges to fight enemies that come to disturb members in their hill.
They have no wings, no eyes and no gender. Some types may be able to adjust their heads to extend out into trunks that produce or emit sticky substance against enemies to paralyse or kill them.
3. Alate Nymphs- are spare termites should any abnormalities occur to the queen or king termites.
Alate nymphs are developed to replace the queen or king termite. Then termites will wait for the appropriate time, temperature and moisture to fly out from their hills as tussock moths ready to create new hills to start another generation of termites.
4. King and Queen termites
have duties to breed and lay eggs in their hills.
Life cycle of termites start in an appropriate season usually after rain. Their life cycles occur 2-3 times a year. Alate or winged reproductive male or female tussock moths fly out of their nests early in the night to fly around light sources to breed. Subterranean termites which destroy buildings usually fly out of their nests at around 18:30 – 19:30. Then they will leave their wings and dig down underground to construct their hills in the areas with food and moisture. Once the ground has been adjusted as their habitat, two or three days later, single eggs are laid and are increased to become thousands of eggs a day. Eggs will be hatched and larvas will emerge. They cast off their skins as they grow into a fully-grown termites. The first batch of eggs will grow to become non-wing and infertile termites. The chemical called pheromone or the substance produced from the anus of the queen termite that is used to feed larva dictate the caste of termite larva. They may become workers and soldiers. Some of the larva will grow to become nymphs living in termite hills during their growing periods. Once the breeding season arrives, they will grow to become fully-grown tussock moths with long wings that fly out to breed. Some larva grow to become supplementary queen and king termites which will breed and lay more eggs to increase the population of termites in case the king or queen of termites are killed.
Living conditions or ecological conditions as well as the eating habits of termites differ depending on the kind and type of termites. They may be categorised into 2 types based on their habitats;
1. Wood Termites
Throughout their lives, wood termites live and eat in the wood. They do not construct pathways to connect to the ground. The general feature that indicates that there are termites in this group damaging the wood is the hard object in round/oval shape in the wood or it may fall out through a hole on the wood surface. We can further divide this type of termites into sub-groups depending on the conditions of wood moisture that termites damage;
1.1 Dry-wood Termites (Dry-wood Termites)
this type of termites live in dry wood or wood that has been in use for a long time and has low moisture. Normally, we rarely find this type of termites outside the wood. However, we usually find hard objects in round/oval shape piling up on the ground near damaged pillar bases, walls or wooden structure. Normally this type of termites only damage the inside of the wood leaving the wood surface intact in the form of thin films. From the outside, it looks as though the wood is still in good conditions.
1.2 Damp-wood Termites:
This type of termites usually live in and consume the wood of perennial trees or seasonal plants with high moisture.
2. Ground Termites
This type of termites live in the ground. They then find food on or above the ground. They usually create pathways in the kind of tubes to cover themselves. This is to protect them from losing moisture and from enemies that may come to them. They can be further divided into 3 sub-groups namely;
2.1 Subterranean Termites:
These termites live and construct their hills underground. Their species include Coptotermes, Microtermes, Ancistrotermes and Hypotermes.
2.2 Mound-building Termites:
These termites construct medium to large mounds on the ground. Their species include Globitermes, Odontotermes and Macrotermes.
2.3 Carton-nest building Termites:
These termites construct small nests on or above the ground for instance on tree branches, on the trees, electric poles or other structures inside buildings. Their species include Microcerotermes, Termes, Dicuspiditermes, Nasutitermes and Hospitalitermes.
Food Sources of Termites may be divided into 4 categories;
most termites eat wood, barks, scrap wood, leaves or other materials with cellulose as their components. In the digestive system of a low-level termites, there are protozoa. In high-level termites, microbes such as bacteria and fungi live in their digestive system to help digesting cellulose or other types of compounds into nutrients beneficial to termites.
Methods to control termites
Most termites have various ways of destroying houses and buildings for instance along the cracks of concrete floors, stairs or joints between concrete floors and building walls, along the main water pipes, along the drainage pipes and along the electrical tubes. Methods and procedure to prevent and eradicate termites are as follows;
1. Pathogenic Agents using fungi, bacteria and earthworms.
2. Chemical Control using termiticides to spray or compress down into the ground. Methods include using bait, organophosphate chemicals, synthetic pyrethroides and other groups of chemicals.
3. Non-chemical Control using metal plate, smooth-surface metal plate, ground stones, ground glass and wood that is enduring by nature.
4. Bait kills termites continuously through insect growth regulator or a slow-reacting chemical with a special feature that attracts termites.
5. Light Tray is used to attract or drive out tussock moths to reduce the number of termites that will breed and construct new nests.