You are among the growing number of homeowners who are seeking less toxic alternatives to the conventional methods of dealing with household pests. According to Sheila Darr, executive director of the Bio-Integral Resource Center, a non-profit organization formed in 1978 to provide practical information on least-toxic methods for managing pests, the effectiveness of the liquid nitrogen method is not as well documented as some of the other alternatives. According to Darr, one of the most effective and least-toxic alternatives is one that uses heat. This is a system wherein propane space heaters blow hot air through ducts into a tented structure, thus raising the ambient temperature to about 150 degrees. That brings the core temperature of the wood-framing members to about 120 degrees. That is all that is required to slay those little varmints. Plus, the heat is not harmful to humans or to the structure or its contents, although it may be a good idea to remove all of your old Tony Bennett albums and any electronic equipment susceptible to damage through heat. Technicians also warn that candles or thin sheets of plastic should be removed as well.