Whilst the good old donger still has a place in the inspector’s toolkit, researchers are now investigating more advanced methods of termite detection within timber.
Low power microwaves for termite detection
Wooden power poles are susceptible to wood decay and termite attack. Structural failure of power poles can have serious, expensive and potentially life-threatening consequences. The 2014 Perth bushfire that destroyed 57 homes (fortunately with no lives lost) was caused by a power pole failure due to termite damage on private property. Both the property owner and maintenance contractor were held liable. In a bid to minimise the fire risk, Australian researchers have developed a new device that uses very low power microwave energy to detect damaged power poles.
Testing of power pole integrity is somewhat subjective and involves ‘sounding the timber’ using a donger or tapping device, making visual observations and drilling holes to inspect the shavings. Successful assessment is not guaranteed even for experienced termite professionals, but with variable skill levels in pole inspectors, poles with damage are often missed. In addition, drilling into poles not only causes damage, but can itself introduce decay, fungi and sometimes termites into the timber.
Australian researchers evaluated two low power microwaves systems, one a ‘look through’ system that required sensors to be positioned either side of the pole and a second, radar-based system that only has to be positioned on one side of the power pole.1 A key requirement is that the systems need to penetrate the complete depth of the wood (some commercial products can assess wood integrity but only to a depth of a few centimetres).
Both systems work on the principle that the breakdown of wood by termites and wood decay affect the wood structure, in turn affecting the dielectric properties of the wood. This impacts the microwaves passing through the wood and creates a distinct profile compared to sound wood. Both systems were 100% accurate in picking up termite activity and decay. In fact, the radar-based system proved very sensitive, even picking up active termite movement as per other commercial termite detection devices. With assessment of a single pole taking a little over one and half minutes, this technology offers significant benefits to the power utility industry and potentially to the pest management industry as a termite inspection tool.
Further reading on termite detection techniques:
Termite detection dogs
An introduction to termite detection dogs.
1 Brodie, G., Thanigasalam, D.B., Farrell, P., Kealy, A., French, J.R.J., Ahmed (Shiday), B., 2020. An In-Situ Assessment of Wood-in-Service Using Microwave Technologies, with a Focus on Assessing Hardwood Power Poles. INSECTS 11. https://doi.org/10.3390/insects11090568