Pesticides may be useful when non-chemical methods fail to
provide adequate control of pests and when pest populations reach
a level of economic injury. The suffix "cide" literally
means kill. The term pesticide refers to a chemical substance that
will kill pests. Since it is physically impossible to eradicate an
entire population of pests, pesticides are used as a tool to
control or manage pest populations to a level of tolerance.
Because of government regulations, chemicals used to attract or
repel pests and to regulate plant growth or function are also
classed as pesticides.