Termites in the Canberra region
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Termites are often incorrectly called 'white ants'. The workers have soft whitish bodies, are wingless, sterile and blind. The reproductive stage is winged with compound eyes. They are social insects like ants and bees. Only a few of the more than 300 species found in Australia are responsible for structural timber damage. In the ACT region there are approximately 30 kinds of termites, although only a few cause extensive damage to sound timber. The two species that do most damage are Coptotermes frenchi and Nasutitermes exitiosus. C. acinaciformis can also cause severe damage but are not common. Heterotermes ferox can sometimes be found feeding on weathered paling fences and Porotermes adamsoni nests in living eucalypts and damp wood.
Many householders worry unnecessarily when they find termites in fresh firewood. These termites are unlikely to pose a hazard to buildings as they are unable to survive on their own in small dry pieces of wood or invade structural timbers. Others could be small colonies of dry wood or damp wood termites that do not attack buildings. It is possible that large blocks of firewood, or intact logs could harbour a Coptotermes nest which would be difficult to detect. It is unwise to stack large timber next to a house or fence if it is likely to contain termites. Only chopped firewood should be stacked so that termites, if they are present, will dry out. Termites generally occur where houses have been built among the trees of original eucalypt woodland. Small eucalypts regrown from stumps can house colonies of Coptotermes frenchi, as they commonly nest in tree trunks and stumps. Coptotermes acinaciformis and Nasutitermes exitiosus are also associated with trees.
Termites can be present where no original eucalypts remain. Adult termites of Coptotermes frenchi can fly from nests and set up new colonies in places like old railway sleepers or thick layers of wood chips (at least 15 cm deep). Coptotermes frenchi and Nasutitermes exitiosus can establish nests if winged adults discover a damp area in the house, such as a shower recess or where the hot water system has leaked. They survive because water is readily available. Porotermes adamsoni can thrive in damp situations but won't attack dry sound timber.
Control of termite infestations in the past has been accomplished by the use of organochlorine pesticides. These pesticides were used extensively in agriculture and for urban pest control in the 1960s and 1970s. Their use has been progressively phased out in the majority of Australian states and territories due to their environmental persistence and ability to accumulate in the food chain. The use of organochlorine pesticides in the ACT, such as chlordane, heptachlor and DDT has been prohibited since 1 December 1993. Chlorpyrifos and arsenic dust are alternative chemicals which can be used by licensed pest controllers for termite control. New methods of termite control in buildings include non-chemical physical barriers such as granite screenings and fine stainless-steel mesh.
Only pest control firms holding Environmental Authorisation issued by the Environment Protection Authority will be permitted to inspect trees for termite activity on land managed by TAMS and to destroy nests that are a suspected source of infestation to nearby structures.
Nests will be considered as a possible source of termite attack if they are located within 60 metres of structures under attack and the termites in the nest are of the same species as those identified in the infested area. Residents requesting termite inspections of trees on land managed by TAMS will be responsible for the cost of the inspection if no termite nests are found. Pest control firms inspecting trees or mounds on TAMS' land for termites, must follow the inspection techniques outlined in the Australian Standard 3660-2000 and the Guidelines for Termite Control in the ACT.
Where a pest controller locates a nest on public land within 60 metres of a residence, TAMS will be responsible for the cost of the inspection and the destruction of the nest. The pest controller must obtain permission from TAMS to destroy the nest. The pest controller must provide TAMS with a written quote that details the site location, number of nests to be treated and termiticide to be used. If the quote is acceptable, TAMS will contract the pest controller to undertake the work. A pest control firm must have current Environmental Authorisation under the Environment Protection Act 1997 and must adhere to conditions under the Authorisation. In addition, the pest controller must hold a recognised qualification in termite control or a current NSW pest control licence, be employed by a registered ACT firm and preferably hold a permit to apply arsenic dust in the ACT. Nests must be destroyed by following the procedures outlined in the Australian Standard 3660-2000 and the Guidelines for Termite Control in the ACT.
When entering land to destroy nests on behalf of TAMS, a pest controller must adhere to any conditions applied by TAMS. Nests must be destroyed within fourteen days of TAMS being notified in writing by the pest control firm. Trees or shrubs on TAMS land must not be damaged during the nest destruction process other than drill holes (12-19 mm diameter) in accordance with Australian Standard 3660–2000. All auger holes drilled in trees on public land (including trees inspected and treated for termites) must be plugged with a non-toxic acrylic caulking compound, such as bathroom sealant or antifungal agents specifically designed for this purpose. Do not use dead wood such as dowelling as it prevents the tree from healing or silicon sealants as they contain harmful solvents which can damage the tree. Where a termite nest is not located, private leaseholders may consider the installation of a chemical soil barrier to prevent possible future termite attack of their residence from the soil. Any precautionary action must be undertaken on the lease holder's land, at the lease holder's expense and must follow the procedures outlined in the Australian Standards 3660 - 2000 and the Guidelines for Termite Control in the ACT.
Detection and eradication of nests
Nasutitermes exitiosus is almost invariably a mound builder in Canberra. If N. exitiosus is found it is likely there is a mound within 30-50 metres of the infested area, often in adjacent bushland. Nests can be destroyed by physically breaking up the nest and spraying with a registered insecticide and filling the cavity with clean soil. Coptotermes frenchi, Porotermes adamsoni and occasionally C. acinaciformis mostly nest in old eucalypt tree trunks.
If these termites are detected, all large eucalypt trees (trunks greater than 30 cm in basal diameter) or stumps within 60 metres should be checked. One indication of termite activity within trees is the presence of hollow broken branches. This is only indicative and a more reliable method is to test by drilling the tree. A drill auger (not larger than 19 mm diameter) should be used to bore holes towards the centre of the tree. If termites are present the centre will be hollow or filled with 'mudguts' and the auger will suddenly penetrate the tree easily. A thermometer may be used to determine if the nest has been located. Nests are a constant temperature of 300C.
To determine if termites are still active within the tree, termites may appear on the auger or a length of dowel or long piece of grass can be inserted into the auger hole and left in place for several days. The dowel or grass is then withdrawn and checked for termites. Trees found to harbour termites should be treated with insecticidal emulsion administered through the auger hole or with arsenic trioxide (only by licensed operator) or other registered products. All auger holes drilled in trees on public land (including trees inspected and treated for termites) must be plugged with a non-toxic acrylic caulking compound, such as bathroom sealant or antifungal agents specifically designed for this purpose.
Do not use dead wood such as dowelling as it prevents the tree from healing or silicon sealants as they contain harmful solvents which can damage the tree. A drop-off in termite activity in the feeding area should occur within a few months of nest treatment. If termites still persist for twelve months or more alternate treatment such dusting with arsenic trioxide or the installation of barriers will be necessary.
Installation of barriers
The installation of barriers, either physical or chemical, prevents termites from entering buildings. Houses with suspended floors can have termite caps fitted to piers and shields fitted on foundation walls. Also the soil under and/or around the house can be treated with insecticide. Termite caps should be checked regularly (every six months) for the presence of galleries around the caps. If galleries are present termites should be identified leaving the infested area as undisturbed as possible. Once termites are identified, a strategy for control can be developed usually in the following priority order:
- detect and destroy nest;
- apply registered termiticide (by a licensed operator) to the infected area, with minimal disturbance, to kill a distant colony that cannot be located; and
- installation of barriers.
It is rarely feasible to fit termite caps and shields to an existing building, but installation of a chemical barrier is reasonably straight forward if the building has a suspended floor with adequate clearance. A 30 cm strip of soil 30 cm deep around all walls, piers and pipes should be treated with insecticidal emulsion. If there is insufficient space to work under a building floor there are two main alternatives:
- Spraying with insecticide. The disadvantage is that spraying contaminates the whole under floor area and dosages at vulnerable points cannot be controlled closely.
- Lift floorboards and treat around exposed walls and piers. This may be a feasible option where flooring has been damaged and needs replacing.
References: Watson, J.A.L. 1988. 'Termites in the Canberra Region', CSIRO, Division of Entomology, Canberra; and Termite Australian Standards 3660.1 - 2000 Workshop, held by Australian Environmental Pest Managers Association and Australian Institute of Building Surveyors, 4 May 2001.
The Environment Protection Authority will collect small quantities of unwanted chemicals from ACT households free of charge. To arrange collection of chemicals residents should call Access Canberra on 13 22 81.
Businesses should contact the Environment Protection Authority for advice.