Termites are a highly destructive group of insects found in the tropical and subtropical regions. There are 3 groups of termites, drywood termites, dampwood termites and subterranean termites.
- Drywood termites cause structural damage to the timber and wood used in construction of buildings. They do not need access to soil to survive and are less dependent on moisture compared to the 2 other groups of termites.
- Dampwood termites are found on decaying wood like dead tree stumps or decaying wood.
- Subterranean termites build their nests in soil and depend on soil for moisture. They are the most destructive of the group and cause most of the damage to the buildings and wood structures. They often produce mud tubes while they move upwards on wood surfaces. The mud tunnels shelters the termites from desiccation.
Termite workers look for cellulose which is their main food source and starts to move upwards while foraging. They start to feed on the portion of wood that touches the soil surface and move upwards. Since termites are generally concealed and their presence is often undetected, the extent of damage to structural timber can be severe before an intervention is done. Once termites have entered a building, they do not limit themselves to wood; they also damage paper products, fabrics, carpets and other materials that contain cellulose.
Termites are locally known as "white ants" due to its similarity in appearance to ants. Though the sexually mature termites called alates look like w inged ants but there are some differences between these two insects.
- The antennae of ants is elbowed which are bent at an angle while the antennae of termites look like a string of beads.
- Ants have a constricted waist between the thorax and the abdomen while termites have a broad waist.
- The forewings are larger than the hind wings of alate ants while the fore and hind wings are of the same size in alate termites.
Termites are social insects and live in colonies with different castes, the royal pair (king and queen), soldiers, workers and immature stages
- The soldiers and the workers in a colony consist of the largest number of individuals and are blind. The female workers are sterile and cannot reproduce
- Worker termites forage for food, store food and maintain the nest and brood. Workers are the main caste in the colony and are responsible in digesting cellulose. Workers feed the other members of the colony with substances derived from the digestion of wood, either from their mouth or anus. This process of feeding of one colony member by another is known as trophallaxis
- The soldiers protect the colony and have anatomical and behavioural specialisations, providing strength and armour which are primarily useful against attack and to protect the colony. Many soldiers have enlarged jaws that help in defense but cannot feed themselves , so like juveniles , are fed by workers. The wide range of jaw types and big globular heads provides methods that can effectively block narrow termite tunnels
Termite Life Cycle
- Sexually mature termites develop wings to become alates from the juvenile stages before nuptial flight. Under conducive environment, when alates receive the proper cues (warm temperatures, bright sunlight, low winds) they will leave the colony and fly away to start their own colonies
- The exodus of alates from a colony, known as a dispersal or nuptial flight, is commonly referred to as swarming; so alates are often referred to as swarmers
- Male and female termites shed their wings and will pair up when a suitable mate is found. Then they will search for a suitably damp piece of wood or soil where they will start their new colony
- At maturity, a queen can lay a huge number of eggs. In some species the queen can add an extra set of ovaries during each moult and may have a greatly distended abdomen. The distended abdomen increases the queen's body length to several times its normal size before mating and reduces her ability to move freely
- Termites undergo incomplete metamorphosis. Freshly hatched young appear as tiny termites that grow without significant morphological changes (other than wings and soldier specializations)
- Some species of termite have dimorphic soldiers (up to three times the size of smaller soldiers)
Asian Subterranean Termites (Coptotermes gestroi)
- They are the most destructive of the subterranean termites and attack building and structures. They are similar in habitat and anatomy to the Formosan subterranean termites (Coptotermes formosanus)
- They are cryptic species which do not build mounds so detection of this species is quite difficult and challenging
- It is also called as the "Philippines milk termite"
- The body of the worker termite is small, white and translucent as are the limbs
- The soldier is larger and also white but the ovoid head, the forward pointing mandibles, the prothorax and the front segments of the abdomen are dark brown
- There are two small pale spots on the head adjacent to the antennae. On the forehead there is an opening called a fontanelle which can extrude a white secretion used tor defense
- The lateral profile of the top of the head just behind the fontanelle shows a weak bulge in C. gestroi that is absent in C. formosanus
- The alates of C. gestroi are slightly smaller than those of C. formosanus
- The head, pronotum, and dorsal abdomen of C. gestroi alates are dark brown, while those of C. formosanus are entirely a lighter yellow-brown or orange-brown. The darker pigmentation of the C. gestroi head provides a contrasting background tor two light patches on the face called antenna! spots. In C. formosanus the antenna! spots are barely, if at all, visible
- The length of wing hairs is somewhat shorter in C. gestroi than in C. formosanus
Black Subterranean Termites (Macrotermes carbonarius)
- They are mound-building species and do not cause too much damage to structural entitres
- This is the largest termite in South East Asia and these large termite species can attain 18-19 mm in length. Winged kings and queens can be about 30.5 mm from head to wingtips, with a wingspan of at least 50.8 mm
- The bodies of both workers and soldiers are very dark, nearly black
- Male workers are larger than female workers
- As in most Macrotennes sp, there is dimorphism for both workers and soldier castes where two sizes are found
- These termites collect mostly dead grass, twigs, and other plant debris which is hauled below ground into the nest
- Small workers chew up the plant material and then deposit their droppings on masses of sponge-like fungus
- The spores, or reproductive bodies that sprout on the outer surface of the fungus, are then fed to the younger termites in the colony
- Older termites eat the remains of old fungus
- Soldiers are aggressive, and readily rush out to confront any intruders if their nest or foraging columns are disturbed
- Their soldiers can deliver a painful bite with their large mandibles, but they do not sting
Perimeter Subterranean Termites (Ancistrotermes)
- These are found in and around perimeters of buildings and structures
- They are smaller in size compared to the other subterranean termite species
- Microtermes species constructs some of the most exquisite and beautiful fungus combs of any termite
- Workers are dimorphic, but soldiers may or may not be
Termite Management Program
- Termite management relies heavily on early detection of termites
- Wooden objects should not be left exposed to damp soil
- Wooden boxes, old newspapers and fabric should not be left on the floor for extended periods of time
- Proper regular inspection for the presence of termites needs to be done. If mud tubes are observed then they should not be disturbed or destroyed since termites will avoid those disturbed areas and chemical treatment might not be effective
- Baiting techniques using cellulosic material is often practiced where monitoring stations are placed around the perimeter of a buildng
- Chemical application of a non-repellent termiticide is effective in controlling termite colonies