Mosquitoes have existed for over 30 million years.  There are about 3,000 different species throughout the world.  Approximately 165 species can be found in the United States.  All mosquitoes require water to develop but they can be found breeding in all types of water from heavily polluted to clean, from small amounts of water held by leaves, to lakes and even pools or streams that have a limited flow.  However, there are some areas where mosquitoes are not likely to propagate including fish bearing waters and moving, flowing, or agitated water.  Areas with shallow perimeters, especially areas shaded from the sun and not subjected to water movements are very likely to produce mosquitoes.

Mosquitoes are insects that belong to the order Diptera simply characterized as "those having two wings."  Other members of this order are the crane fly, midge fly, horse fly, and stable fly.  Mosquitoes are different from flies because they have scales on their wings, legs, and other parts of their bodies.  Also, mosquitoes have a long proboscis, a straw type structure with a sharp end.  In female mosquitoes, the proboscis enables them to pierce the skin of animals to obtain a blood meal.  The proboscis has two tubes--one injects her saliva containing blood thinners and the other draws blood.  It is the saliva that causes a bump on the victim's skin because it triggers an allergic reaction that has the potential to hospitalize some people.  The harmless make mosquitoes also has a proboscis, however, they use it only to feed on pollen and plant juices.

The mosquito goes through a complete metamorphosis meaning that there are 4 stages to their life cycle:  egg, larva, pup, adult.

The eggs are laid either directly on water, on the sides of water holding containers or in areas that will eventually be underwater depending on the mosquito species.  Some species lay their eggs individually and other lay them in rafts of 50 to 400 eggs per raft.  In proper conditions, eggs can hatch in 1 to 5 days but some will lie dormant over the winter and can withstand very cold temperatures.  They will hatch when warm, wet weather arrives.

The larval stage will last from three days to four weeks depending on the species, water temperature, availability of food and type of container (e.g., black tires can speed up the process by absorbing heat from sunlight.)  During this stage the larvae will go through four instars in order to increase in size.  The larvae have three weaknesses.  They have to live water, breathe air, and are constantly feeding.  The larvae breathe air through a siphon or breathing tube at the base of their tail.  The larvae of some mosquito species use specialized siphons to puncture the submerged roots of plants to get air and therefore they never need to come to the water surface.  Larvae feed on bacteria, water mites, water fleas, and other organic debris by filtering small particles out of the water with tiny brushes on their mouth parts.

The pupal stage will last from one to three days depending on the water temperature.  This stage is unique because the pupae do not have a mouth and do not eat.  The reason for this is that their digestive system is changing from one that handles small food particles to one that can feed on liquids.  Also, during this stage the legs, wings, eyes, and other adult characteristics are developing.  At the end of this stage, the pupa's skin along its back splits open and the adult mosquito gradually emerges through the opening.  This process takes about five minutes and the adult mosquito will stand on the waters surface for a few minutes while its body hardens and its wings expand.  The water must be very still for this process to occur.  Thus, developing mosquitoes are usually not a problem where the water is moving or wind action causes ripples.

The length of the adult stage varies depending on species and gender.  Male mosquitoes usually live for only six or seven days but the females can live for up to five months.  Only the female mosquito bites and for most species, she must have a blood meal before producing a new batch of eggs.  Once the female has a blood meal, she can lay 100 or 200 more eggs.  The females will obtain their blood meal from a variety of animals including birds, deer, cattle, and dogs.  Some species will only feed on certain animals such as frogs and others have no preference.  Very few mosquitoes actually prefer to feed on humans.  Mosquitoes are responsible for carrying several diseases, perhaps the most common today in West Nile Virus.