Two years ago a field experiment was designed and installed to evaluate the effectiveness of Granitgard, the commercial name of a grade of crushed granite rock, as a termite physical barrier when retrofitted around 'mock-up' buildings. The field station is located at Walpeup in the semi-arid mallee region of northern Victoria (360 km north of Melbourne), and there are several indigenous subterranean termite species at the site. After 20 months, no foraging by Coptotermes species has occurred in the 'mock-up' buildings. It seems that these termite species (the most economically important termite species in Australia) have not breached the trenches filled with Granitgard alone, and with a mix of Granitgard and chlorpyrifos. While it may be too early to declare that retrofitted Granitgard around existing buildings prevents subterranean termites gaining access to the building, there is no doubt that Granitgard does affect subterranean termite foraging behaviour. However, this effect is accomplished without detrimental environmentally side-effects. Granitgard is approved as an alternative to soil chemical barriers when installed under newly constructed buildings in the latest Australian Standard (AS 3660 -1993). The current results of the retrofitting experiment suggests that there may well be a practical role for such a physical barrier in the protection of existing buildings as well. This paper describes the results of the field evaluation of Granitgard when used as a retrofitted barrier around 'mock-up' buildings after two years in a field test. We discuse the implications of these findings and where they fit into future integrated pest management strategies for termite control.

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