Humans have been using insecticides for thousands of years. The Egyptians used unspecified chemicals to combat fleas in their homes about 3, 500 years ago, and arsenic has been used as an insecticide in china for at least 2, 900 years. Insecticide is a substance that kills insects. Insecticides are sometimes called pesticides. But pesticides include substances used to control mice, weeds and other pests besides insects. Insects harm human by transmitting diseases. Diseases such as malaria and typhus can be controlled by using insecticides to treat the breeding places of the insects that spread the diseases.
Insecticides are usually classified as organic, inorganic, botanical and microbial insecticides. (World Book Encyclopedia, 1998)
An insecticide is a substance used by humans to gain some advantage in the struggle with various insects that are considered “pests”. In the sense used here, a pest insect is considered undesirable, from the human perspective, because: (a) it is a vector that transmits disease causing pathogens to humans (such as those causing malaria or yellow fever), or other diseases to livestock or crop plants; or (b) it causes a loss of the productivity or economic value of crop plants, domestic animals, or stored foodstuffs. The abundance and effects of almost all insect pests can be managed through the judicious use of insecticides.
However, the benefits of insecticide use are partly offset by important damages that may result. There are numerous cases of people being poisoned by accidental exposures to toxic insecticides. More commonly, ecological damage may be caused by the use of insecticides, sometimes resulting in the deaths of large numbers of wildlife.
Almost all insecticides are chemicals. Some are natural biochemicals extracted from plants, while others are inorganic chemicals based on toxic metals or compounds of arsenic. However, most modern insecticides are organic chemicals that have