Webster defines a pest as any plant or animal that is detrimental to humans or human concerns (especially in agriculture or livestock production). Pest control has been a serious issue for humans since the dawn of civilization. Through the centuries, mechanical, biological, cultural and chemical controls of pests have evolved. The reasoned use of pesticides dates to at least 2500 BC, when sulfur was used as a control of mites and insects. As technology advanced, control measures were adjusted and new techniques and materials were discovered, and those changes greatly accelerated in the previous century.