Insecticides are a form of pesticides that use chemical agents to control insects. In many cases this control means death. Insecticides are an important part of the world today because of their effects on the world's food supply and diseases carried by insects. These chemicals are also poisonous to people and the regulation of the substances is a heated topic. Many regulations are in place that are helping improve the safety of the environment and people. Many different types of insecticides exist. Insecticides are very influential to people and the environment. It is important to control the use of these substances and prioritize the health and safety of people. 
What is an Insecticide?
An insecticide is a chemical agent that controls insects. These chemicals control insects by killing them or by stopping them from performing destructive behaviors. Man-made or natural, insecticides target pests that harm mankind in some way. Whether it be the detrimental effect of locusts on a field of wheat or a bee hive in a child's treehouse, insects often in some way or another affect people's lives.
Insecticides are a very important part of the world today. With a population of over 7 billion people, a strain is put on the earth's ability to provide food. Agricultural advancements have made feeding the population much more efficient in the past 100 years. However, with these technological advancements, there have also been very serious complications. Insects are one ever present problem.
Insects are present on the farms of men and by eating, destroy farmers' crops for food. So, this creates a problem for us humans who need the food to survive. Humans began to develop an answer to this dilemma. World War II was an important time for insecticide development. It was then that DDT was first introduced as a tool for insect control.  Many other effective insecticides followed DDT and had positive effects on food issues and many insect carried diseases. However, as time went on insects began to build a resilience to some of the insecticides. Also, many studies showed how some chemicals negatively affected the environment and the many dangers some insecticides posed to human health. This resulted in the banning of many insecticides by the Environmental Protection Agency and other agencies protecting the environment. In result to the bannings and insect resilience, safer and more effective insecticides continue to be produced. Insecticides are fundamental to the overall success of the world's food supply and agriculture. 
Applications and Mode of Penetration
There are a number of ways that one can apply insecticides. The choice mainly depends on the type of chemical, type of insect, terrain and size of area affected, cost of application, and different regulations and laws. Consumers can go to their neighborhood hardware store and pick up numerous types of insecticides. Brands like Ortho, Bayer, and Scott are just some of the big names in pesticides and insecticides. These types of insecticides are applied easily by a consumer. Many feature pumping options for spraying a liquid solution and others are simply powder like substances you can put on the ground. If you don't want to mess with chemicals yourself, there are professional pest control servicemen. Companies like Orkin will send specialists to your home to apply insecticides and pesticides for you. They carry industrial application tools. For example they have the solution stored in a gadget on their back and a pump nozzle in their hand.
Application processes for large agricultural establishments differ from the household applications. Aerial application, or crop dusting is the best method for large crop growers. Planes are often made especially for crop dusting but other small planes and even helicopters can be modified for the job. The planes are equipped with a spraying systems located beneath the wing. These systems are capable of dispersing fertilizers, pesticides and insecticides, and fungicides. Once loaded up with their sprays the planes take off and fly very low to the ground dispensing the chemicals right on top of the crops. 
Insecticides poison insects. There are numerous ways that the chemicals enter the insects' bodies. When controlling insects that use their mouths to bite and chew plants, stomach poisons are commonly used. These are ingested through the mouth when insects eat the plant with the insecticide. When facing insects that do not use their mouths for eating, per say an aphid, contact poisons are used. These penetrate the outer membranes of insects and then take effect. The other type of penetration is fumigation. Fumigation takes place when the insecticide enters the insect's respiratory system through its spiracles. 
Insecticides that contain carbon, hydrogen, and chlorine are classified as organochlorines. Some other common names used for this classification of insecticides are as follows: chlorinated hydrocarbons, chlorinated organics, chlorinated insecticides, and chlorinated synthetics. The diphenyl aliphatics, including DDT, DDD, dicofol, ethylan, chlorobenzilate, and methoxychlor, are some of the most common and oldest organochlorines.
Between 1940 and 1973, more than 4 billion pounds of DDT were used throughout the world.  DDT was effective in combating malaria, typhus, and other human diseases caused by insects. The chemical was effectively used among civilian and military populations, insect control for agriculture and livestock, and even around the house and gardens. Its use was largely halted in 1973 when the U.S. Environmental Protection Agency issued a cancellation of DDT. The cancellation was "based on adverse environmental effects of its use, such as those to wildlife, as well as DDT’s potential human health risks" (epa.gov)The EPA is still trying to end use of DDT worldwide. It is very harmful to the environment and to people. DDT is still used to combat mosquitoes carrying malaria but safer methods that limit the spread of DDT are being worked on. 
Cyclodienes are another important group of organochlorines. The most used cyclodienes include chlordane, aldrin and dieldrin, heptachlor, endrin, mirex, endosulfan,and chlordecone (Kepone®. Like DDT, these insecticides was first used after World War II. Cyclodienes are quite persistent against insects. They help prevent the occupation of larvae, commonly termites, in wood as well as soil. They have been known to protect wooden structures for over 60 years. These chemicals were the longest lasting, most effective, and most economically sensible termiticides ever developed. However, insects began to grow resistant to the effects and the EPA cancelled the agricultural use of cyclodienes between 1975 and 1980 and then between 1984 and 1988 their use as termiticides was also cancelled. 
Organophosphates are insecticides with organic compounds containing the element phosphorus. Every organophosphates are synthesized or derived from a phosphorous acid. These insecticides are regarded as the most toxic insecticide to vertebrates. Like organochlorines, these were first used as insecticides after World War II. The discovery of these was made in search of a nicotine substitute in Germany who was in a shortage of nicotine. Closely related to many nerve gases, organophosphates are dangerous insecticides. Many are also chemically unstable. They attack the nervous system and cause rapid twitching of voluntary muscles resulting in paralysis. 
Pesticides play an important role in maintaining yields of agricultural crops. However, the residues from pesticides can potentially be harmful to humans if they get into the food we eat. A pesticides expert at EFSA explains the measures that are in place to reduce the risks.
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