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Termite Control, Termite Inspection, Pest Services, Termite Treatment |
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Termites
In Melbourne, there are two main types of pest termites: Dampwood Termites and Subterranean Termites (Coptotermes spp.). Both species are timber attacking species, with the latter the more destructive, because it attacks dry timber as well as damp, whereas the former attacks only damp wood (as the name suggests) and is seldom found in dry wood in well ventilated and clean areas.
People often mistake the cause of damage to timbers in their homes, believing it termite damage, when in fact it may be caused by beetles, borers or decay/rot. However, it is important to have the damage inspected by a professional pest controller to confirm the cause of the damage when in doubt.
Home owners purchasing an existing house, or building a new house, should be aware of the risk of termite damage, and have the house inspected for termites before purchase, or pre-treated during the building process to prevent possible future termite infestation. There are areas around Melbourne more prone to termite infestation than others, and those homes in the high risk areas should be regularly checked, pre-treated, or have a termite control treatment applied to the property to avoid possible infestation if concerned, or hear of a neighbouring property with a termite infestation.
Depending on the type of soil, available food sources and moisture content, the range of subterranean termites from the central colony can be up to 50 metres through tunnels to timber food sources. The central colony may be on another property, however the termites range can extend beyond that property to others if a good food source is found. In the case of wood eating species, decayed or decaying wood appears to be more attractive than sound, dry wood.
This food source is often trees (and especially tree stumps) that have high moisture content or are decaying. Other timbers from fencing, decking, and house stumps in moist soil are also a possible food source reached via subterraneous passages by the termites.
Dampwood termites particularly, can be partial to wet area sub-floors, such as bathrooms and laundries, where the moisture content may be high in the timbers, and are particularly apparent in houses where sub-floor ventilation is poor and the consequent high humidity has aided fungal growth on the timbers, allowing the termites to infest the moist and decaying timbers, as well as providing high humidity conditions that are essential to their foraging.
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Biology and Behaviour
Termites are primitive insects which have a social organisation similar to ants, and some bees and wasps. They are similar to ants only in their habits of living together and their small size, but actually, termites are more closely related to cockroaches and grasshoppers. As with ants and bees, the termite colony consists of several castes, which differ physically and have their own particular duties to perform. All the duties are directed towards the maintenance and survival of the colony. The castes are: The queen and king, workers, soldiers, and the reproductives.
The Queen and King
The queen and king are the original winged reproductives (alates) that left the parent colony during the colonizing or dispersal flight. Their function in the colony is reproduction. After leaving the parent colony, they drop to the ground, shed their wings (de-alate), seek out a suitable nesting site, mate and commence to form a new colony. In the case of many of the subterranean species, moisture and decaying wood are critical during the very early period of development. Timber in moist ground or a rotting scar at the base of a tree is a favoured nesting area for a potential new colony. The king and queen will care for their young until sufficient workers and soldiers are able to take over the duties of the colony. In a well established colony, the queen’s duty is solely egg laying, and her daily egg production has been estimated to be over 2,000.
For a species such as the destructive pest termite Coptotermes acinaciformis, to reach a potentially damaging stage from a single pair usually requires 3-5 years, but this depends on the site, food and climatic conditions in the chosen environment.
The queen and king live for many years, often over 20, but as the queen ages, her reproductive capacity declines, and the colony may then select developing reproductives to assist the queen and king in their duties.
Workers
The workers are males and females whose sexual organs and characteristics have not developed. They are the most abundant caste in the colony because the workers perform all the tasks except defence and reproduction. It is the workers that do the damage to timber. They are blind, wingless and sterile and they have a thin body covering (cuticle), which makes them susceptible to drying out (desiccation) when they leave the confines of the colony. Workers are the palest individuals in the colony, apart from the eggs and developing young.
Workers leave the security of the colony or the underground tunnels and shelter tubes only when the humidity is high, and then only to search for food sources.
Soldiers
Soldiers are males and females whose sexual organs and secondary characteristics have not developed. Their role is solely defence from ants and other enemies. They have a frontal gland that produces a secretion which is repellant to ants and other enemies and termites. Soldiers are abundant in species that have a large central colony system, but scarce in some other species. Sightless, they have no compound eyes, except in some primitive species where the eyes are poorly developed. Like workers, their cuticle is thin and they are susceptible to dessication and seldom leave the environmental security of the colony and shelter tubes.
There are two types of soldiers: Mandibulate and Nausate. Mandibulate soldiers have obvious and large jaws or mandibles on the head, and Nausate soldiers have a large head that tapers to a point at the front. Their mandibles are small and hidden by the head when viewed from above.
Reproductives
Reproductives are the sexual forms of a colony – the future kings and queens. The young (nymphs) of reproductives grow by successive skin shedding (moults) until they are fully winged alates.
They have compound eyes, are darker in body colour than workers or soldiers, and are often larger. The cuticle of reproductives is denser than that of the other castes, and they are therefore able to resist drying out when they leave the parent colony to establish new colonies.
The colonizing flight often occurs when the temperature and humidity outside is similar to that inside the colony. The warmer months of November and December are usually selected for the colonizing flights, although it may differ depending on the species.
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Food and Feeding Habits
Termites feed on wood, wood products, leaves, bark and grass. If these products are breaking down due to fungal activity or the activity of other organisms, they appear to be more attractive to termites. There are several species of termites that do not attack sound wood, but only wood that is decaying.
The cellulose of wood is digested by intestinal protozoa (single celled organisms) in many species of termites by producing an enzyme, cellulose. These protozoa are present in the lower area of the hind gut and are important in the conversion of cellulose to simpler molecular products that can be used by termites, supplying them with essential carbohydrate.
The worker termites consume the food where they find it. They then return to the colony area where the other castes and younger workers feed on the products from their oral and anal areas. This procedure also ensures the transfer of protozoa to the young termites.
Termites require protein as well as carbohydrate in their diet, and this is usually supplied by the fungi that decay wood and vegetation.
Cannibalism within termite colonies has been recorded, and this more likely to occur where the protein/nitrogen intake is low.
Conditions that favour termite infestation
Subterranean termite attack is often encouraged unwittingly by human carelessness in providing termites with the ideal conditions for their establishment and development.
When a pair of reproductives are seeking a site for establishing a colony, they are exposed to the outside environment, and unless their basic requirements for food, shelter and moisture are met, they die. Of the many thousands of alates that leave the parent colony in flight, few, and often none, succeed in establishing a new colony.
In attempting to reduce the termite hazard, wood in the soil, moisture, and dead trees and stumps are significant factors. Off-cuts of wood left in the soil or used as fill under a patio or bathroom during house construction, provides decaying wood, essential for the establishment of a new colony, and creates an ideal environment for termites.
Also, the use of railway sleepers in landscaping provides termites with decaying wood in moist situations. Pressure treated timbers, mostly radiata pine, are favoured for landscaping, as they are chemically treated to protect the timber from decay and insect attack, and is not attacked by termites.
Dead trees and tree stumps provide a nesting area not only for subterranean termites but also for dampwood termite species. Dead roots left in the soil may also be infested, and these sometimes provide termites with subterranean access to buildings.
Stumps and the root crown of felled trees can be removed with stump grinders, and the area exposed chemically treated if necessary.
Subterranean termites depend on moisture for establishing and maintaining their colonies. Moisture is also required by the wood decay fungi from which termites obtain their protein.
To make the environment less attractive to termites:
- Ventilation of the sub-floor area reduces the moisture content of the air and prevents condensation of water on the wood.
- Leaking drainage and water pipes should be fixed to avoid providing the soil moisture termites require.
- Natural seepage may be reduced by the installation of subterranean drains.
Termite Control
Several species of termites nest in the trunks and root crowns of trees, usually becoming apparent in old trees. Treatment requires locating the nest and injecting pesticide directly into the nest area.
In houses, remove contact between the termites and the timber of the house, improve ventilation where applicable, and treat soil access area with a chemical soil barrier.
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