Insecticides

An insecticide is a pesticide whose purpose is to kill or to prevent the multiplication of insects. 

Insecticides are very widely used in agriculture, as well as in people's dwellings and workplaces. The use of insecticides is one of the major causal factors behind the increase in agricultural productivity in the 20th century. 

Various plants have been used as folk insectides for centuries, including tobacco and pyrethrum. 

Environmental Effects

Some insecticides have been banned due to their adverse effects on animals or humans. 

DDT is an example of a heavily used and misused pesticide. One of the better known impacts of DDT is to reduce the thickness of the egg shells on predatory birds. The shells sometimes become too thin to be viable, causing reductions in bird populations. This occurs with DDT and a number of related compounds due to the process of bioaccumulation, wherein the chemical, due to its stability and fat solubility, accumulates to progressively higher concentrations in the body fat of animals farther up the food chain. The near-worldwide ban on DDT and related chemicals has allowed some of these birds--such as the peregrine falcon--to recover in recent years. 

Misuse of insecticides is a major factor in pollinator decline. 

Some of the newer insecticides are more specific in their actions and are designed to break down into non-toxic components within a few days of application. 

Individual insecticides: 

Chlorinated, several now banned because of their ecological persistence: 
Aldrin 
Chlordane 
Dieldrin 
DDT 
Lindane 
Organophosphorus (chemically similar to Nerve agents) 
Diazinon 
Malathion 
Plant toxin derived: 
Derris (rotenone) 
Pyrethrum 
Neem (Azadirachtin) 
Others: 
Cypermethrin 

Branded products: 
Black Flag (insecticide)