A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest (living organisms that occur where they are not wanted or that cause damage to crops or humans or other animals). Though often misunderstood to refer only to insecticides, the term pesticide also applies to herbicides, fungicides and various other substances used to control pests (insects, mice and other animals, weeds, fungi, bacteria, viruses, etc.).
By their very nature, most pesticides create some risk of harm; they can cause harm to humans, animals or the environment because they are designed to kill or otherwise adversely affect living organisms. Biologically-based pesticides, such as pheromones and microbial pesticides, are becoming increasingly popular and often are safer than traditional chemical pesticides. (Source: EPA / Photo: Flickr)