Pheromones are chemicals that are secreted in the sweat and other bodily fluids of animals, and influence the behavior of the other members of the population. The word 'pheromones' came from the Greek word pherein (to transport) and hormone (to stimulate). Pheromones have the ability to impact the behavior of the receiving individual like vertebrates, insect, and plants. There are also many different types of pheromones like aggregation, territorial, sex, etc.
Mode and Types of Pheromone
Pheromones are secreted or excreted chemical factor that trigger a social response in members of the same species. Pheromones have the ability to impact the behavior of the receiving individual. Some vertebrates,insect, and plants communicate by using pheromones. Also pheromones are ectohormones they act outside the body of the individual that is secreting them. Unlike hormones which usually only affect the individual that is secreting them.
There are eight different types of pheromones. Aggregation, alarm, releaser, signal, primer, territorial, trail, and sex. Aggregation pheromones function in mate selection and other social behavior like defense against predators. Many chemicals, including hydrocarbons, alcohols, aldehydes, ketones, esters, acids, anhydrides, amines, and nitriles, have been identified as insect aggregation pheromones. Alarm pheromones function as a signals that warns other individuals of the presence of danger or otherwise reduce the success of predators.  Releaser function as a quick alteration in the behavior of the receiver. Signal causes short term changes. Territorial helps the recipients to mark the boundaries and identity of an organism's territory. Trail pheromones are used in social insects like ants. The trail pheromones release chemicals to help attracts other ants and serves as a guide. Sex pheromones helps indicate the female availability for breeding. Also it helps male animals convey information about their species and genotype. 
Uses of Pheromones
The most popular use of pheromones is pest control. There are three main uses of pheromones in pest control. The first use is monitoring a population of insects determine if they are present or absent in an area. For monitoring is one of the most important thing for pest control.The second use is to trap insects to remove large numbers of insects from breeding and over populating. Cause the population density of pest insects ultimately help to protect resources such as food or fiber for human use. The final use is to control the insects is to disruption the mating in populations of insects. Synthetic pheromones are dispersed into crops and the false odor plumes attract males away from females that are waiting to mate. Disrupting the mating between male and female will reduce the population of the insects.
Some scientists believe that human have pheromones. Though there is no evidence of a consistent and strong behavioral response to any human producing chemicals. Even now its harder to detect human reactions than those of a silk moth. Since they haven't found any human pheromones, researchers propose another kind of chemical messenger, known as a “modulator” pheromone, that affects the mood or mental state of humans. Even though search for human pheromones continues, scientists have also investigated other potential explanations. Human infants will crawl toward the odor of their mother’s breast, but the infant could just simply be attracted to a mother's personal scent. Despite the failure to identify human pheromones individual companies will not stop making "love potions" purporting to affect human pheromones.
Do Humans Have Pheromones?
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- Yuhas, Daisy. Are Human Pheromones Real? Scientific American Mind. Web. Access April 28,2016.