Termites on the whole are responsible for less than 5% of pole failures in Australia, although this percentage is rising rapidly as decay is being controlled with routine remedial treatments. Termite control in wooden poles is complex, however there are essentially two main issues:
The modern treatments available in meeting environmental criteria are not permitted to have long term residual affects and are not as lethal as in the past.
Termite nests are usually not accessible within the pole, therefore direct contact is restricted.
Generally the traditional method of attempting to directly destroy the termite nest is being altered to a barrier type protection of the structure. There is a range of relatively safe treatments available that can be used without the need for complex safety apparel and restricted licences. In the case of pole inspectors, many are authorised to apply termite treatments at the time of inspection of the pole.
The chemicals contained in Polesaver rods and Bioguard Bandage are an effective termiticide in the localised treatment area.
Termites impact on wooden poles and structures
In general the warmer more tropical climates are areas of higher termite activity. Identifying active termites and the location of nests is an ongoing problem . Often nests can be located a considerable distance from food sources, making selection methods for treatments complex.
Termites and decay are a natural part of the decomposition process. Termites are therefore often attracted to decaying wooden structures, which reinforces the benefit of controlling decay.
How termites live
Termites are social insects living in colonies made up of specialised forms. They are soft bodied and commonly 3 – 10mm long.
A termite colony is made up of different forms of individuals:
The king and queen reproduce sexually. The eggs laid produce all the other individuals within the colony.
Supplementary reproductives may be present and do have the ability to reproduce sexually in pairs of male and female.
Workers build and repair the nest as well as tend to the King and Queen.
Soldiers defend the colony.
Alates leave the nest at certain times to start new colonies.
Nymphs are the youth stage of termites before they grow into either workers, soldiers or alates.
Termites live together in a colony with an organized social structure. Some species such as the destructive subterranean termite( coptotermes aninaciformis) have colonies totalling in excess of 1 million individuals.
Termites exist in the dark. Worker and soldier termites are actually blind. Their nests can be built in trees, underground in the base of trees or as a mound above the ground. They build earthen tunnels from the nest to their food source, although they can search for food in the open during humid nights. The earthen tunnels are normally constructed underground, but occasionally are seen on the surface or in cracks of trees or wooden structures.
The food of the termites includes wood and vegetable material such as grasses and plant debris. The species that attack timber are utilising it’s cellulose as a food source. Termites are particularly attracted to poles in the same way as dead trees when fungal decay is present. Subterranean termites can also attack dry sound wood using the ground as a moisture source. The workers feed soldiers, young nymphs and reproductives with partially digested food. In passing on food gut micro-organisms are also transferred. This close association together with a habit of grooming each other can be exploited when nests are treated with arsenic dust and the poison spread throughout the colony.