Extermination of insects by heat

A method of exterminating wood-destroying insects in situ whose situs is embodied at a substantial depth inside a wooden structural member of an urban structure having surfaces, said method comprising:

• heating an environmentally acceptable gas which does not undergo phase change at any temperature between ambient and the temperature utilized herein, to an elevated temperature;
• applying said heated gas to surfaces of said structure until the temperature of the wooden structural member at said substantial depth reaches a lethal temperature at which said insects cannot survive for a significant length of time, and maintaining said lethal temperature at said substantial depth for a period of time necessary to assure the death of said insects, said heated gas being supplied at a supply temperature higher than said lethal temperature;
• said application of heated gas being accomplished in such a manner that the heated gas circulates so as to provide for improved heat transfer to the surfacer of the structure and to avoid thermal stratification in the structure.