One of the first preparations to use copper in the war against pests is called Bordeaux mixture. In 1882, the French botanist Pierre-Marie-Alexis Millardet discovered that vineyard grapes treated with an unappetizing blend of copper sulfate, lime and water to keep thieves away also killed powdery mildew. It was the beginning of a long tradition of using copper as multi-purpose biocide and helped to start a new chapter in the way man controls his environment [source: Encyclopedia Britannica].
The Environmental Protection Agency (EPA) defines a pesticide as a mixture or substance that destroys, repels or mitigates pests. Copper is an inorganic pesticide that works by oxidizing enzymes, lipids and proteins. This can change the normal role of these agents, making them reactive and toxic, or just changing them enough that they can't be used successfully [source: Freeman].
To control termites with copper-based pesticides, wood used in construction is treated with a special chemical cocktail. The other ingredients in this cocktail have changed over the years as we've come to understand their long-term effects on the environment, but copper continues to be a primary ingredient.
On the next page, we'll take a look at some wood preparations that contain copper.