The Environmental Protection Agency (EPA) defines a pesticide as any substance or mixture of substances intended for the prevention, destruction, repulsion, or mitigation of a target (pest). When discussing pesticides, the correct definition of “target” is important due to the fact that it is often assumed that pesticides only eliminate insects. This is an incorrect assumption. A target is merely the sight of application, which could be a number of things such as: plants, soil, insects, animals and structures. The intended use of a pesticide is not only to eliminate the target, but to do so without harming the surrounding, sometimes fragile non target species.

The way pesticides work is called “the mode of action”. Pesticides with similar chemical composition are grouped in “families”. Chemical families will have a similar mode of action. More specifically chemical families will have similar chemical structure and chemical properties (such as poisoning symptoms). Most pesticides may be placed in one of forty different families.

Pesticides can be broken down into a number of categories, namely: bactericides (for control of bacteria) fungicides (for control of fungus) herbacides(for control of weeds), insecticides (for control of insects) miteacides (for control of mites), molluscacides (for control of slugs and snails) nematic ides (for control of nematodes) rodentacicdes(for control of rodents) and finally virusicides (for control of viruses). Pesticides can be further classified as synthetic pesticides otherwise known as a chemical substance, biological pesticides, such as virus, bacteria, antimicrobials and disinfectants.