An overview of termites

Termites, ants and bees are eusocial insects. This means each termite colony is a ‘living unit’ or a separate “social”. In each termite nest, depending on the species, the number is from a few hundred to a few million individuals. In the world, over 27,000 species of termite have been surveyed while over 80 species have been identified in Vietnam. Among these species, there are only differences in terms of morphology, colony structure and the number of individuals; however, they all live as a community. Each termite population has a functional assignment. For example, for home-invading termites (e.g. coptermes, formosanus shir), adult colony can have more than 10 million individuals.

  1. Structure of a termite colony

The typical termite colony will have a primary king and queen, secondary reproductives (alates), soldiers, workers and nymphs.

Termite life cycle

The King and the Queen
The queen is largest in physical size, attaining mass several times (up to 300 times) that of workers. Her main function is to lay eggs, sometimes thousands in a single day. If elimination methods have not killed the queen yet, the colony will soon increase in size. The queen and the king usually do not leave the nest unless it is flooded, In this case, they can leave the main nest to another one which is more safely.

 

Alates (Winged termites)

In the colony, there are always alates or winged termites. They are the ones that go through the course of several molts. They also go to work as the workers. Every year, during late winter or early spring, male and female ones leave their nest on a mating flight with thousands or even millions of other winged termites. The winged termites are poor fliers, so they usually only fly a few yards from their old nest. Many of the alates are eaten by frogs, lizards, birds or spiders during this mating flight, so relatively few alates survive to find nesting sites, reproduce and form new colonies. The termite colonies produce many alates so that at least a few survive the mating flight. Male and female termites who servive pair up during the mating flight. The female alate releases a pheromone to attract a male for nesting and mating. The winged termites shed their wings shortly after landing and spend the rest of their lives without flight. The male and female termite couple look for a nesting site near moist soil.

Thus, it is important to eradicate possible nesting sites of winged termites to have long-term termite control.

(Winged termites before flying out of the nest)

The soldiers

Soldier termites have distinctively shaped heads and are typically bigger than workers. Their protruding mandibles help them protect their colonies. They have elongated bodies and are pale red, light brown, or white. Soldiers are the protectors of the colony. They guard the termite colony and defend it against predators. Considering soldiers’ large heads and mandibles, they are well equipped to battle insects (typically ants) that invade the colony. An alarm pheromone can signal such an invasion and bring soldiers to the site of the attack.

(Soldier termite in attack position)

The workers:

In most termite colonies, workers are wingless and soft-bodied. They comprise the largest single group ( above 80%) in most termite colonies and are the termites most frequently seen when infested wood is disturbed.
In some termite colonies, the immature termites or the sterile adults are the workers.
Young or recently developed workers usually remain in the colony to do general repair and maintenance work on the galleries, and they are responsible for caring for the queen and eggs. Older workers are primarily responsible for foraging for food away from the main nest. About 10 percent of the workers in a termite colony are away from the nest foraging for food.

For termite species that do not have soldiers in the colony, the older workers are responsible for defending the colony from invaders.

(The workers foraging for food and their internal structure)

  1. Types of termite nests

Different termite species differ in their nest. In terms of termite control, we need to care about the nest location which can be divided into two groups as follows:

– The termite nest is in the wood
In Vietnam, common termites are drywood termites (cryptotermes domestics). Their nest is empty huts with small sand-like piles around as they consume and infest furniture. Based on this characteristic we can detect them. Although they live within the wood, they can also consume books or clothing near their nest. With this species, the number of each colony is about three hundred to four hundred termites.

-The termite nest is related to soil and water
All other termite species when build the nest always have a need for soil or water outside the nest. Most species have a nesting system consisting of a main nest and many patriarchs to tolerate large numbers of individuals. The main nest has the king and the queen. There are many types of nest deep in the ground from 1 to 2m.
The nesting system of the domestic termite (Formosanus coppice) is both under the ground and in the upper structure, sometimes completely located above it, but still has a connection to the water source.
In the case of dams, the porosity of the termite nests affects the durability of the foundation, which is necessary to detect the nest for treatment. The experience in Vietnam is that in the late spring, when mushroom is found, the nests can be digged much easily. For other objects, the porosity of the nest is less affected

Nest of Subterranean termite

  1. The food of termites

Termites are detritivores, or detritus feeders. They feed on dead plants and trees. Termites get nutrients from cellulose, an organic fiber found in wood and plant matter. Wood makes up the majority of the pests’ diet, although termites also eat other materials such as paper, plastic, and drywall. Most species prefer dead wood, but some termites feed on living trees.
Each type of termite has its own dietary preferences.
– Subterranean termites prefer softwoods, but may invade most species of wood.
– Dampwood termites generally stay close to the ground, but will choose moist, decaying wood anywhere it is found.
– Drywood termites are often found in attics and require little moisture in the wood they eat.

(Termites infest wood for food)

  1. Paths of penetration into the building

Termites penetrate into buildings and houses by three roads:
– From neighboring buildings which contain termites, called contact roads;
– From grounds which under the ground already have termite nests and is not eliminated before constructing and building;
– Flying termites: every year from the termite nests, winged termites fly out of the nest and penetrate into the construction work. Many construction works only last two or three years. It can be due to: when backfilling and clearing the construction site, there can be left planks in the ground, which is an ideal food source and nesting for termites. Or when paving, in the foundation already has termite nests, so it only takes two to three years to see termite appearances.

It is important to note that domestic termites can infest all types of normal mortar, except for high strength concrete (> 80), thus the termite can reach all floors.
For many works, termites have appeared in the highest floors such as: 8-floored Institute for child health protection; Hanoi Hotel with termites appearing on the 11th floor; many families on the 4th floor and 5th floor also have suffered from termite damage for books, clothes and blankets.

Termites path

Termites path under the ground

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