Mosquitoes are living fossils believed by evolutionists to have existed around 170 million years ago. Mosquitoes are predators best known as pests by humans because of their bites which cause itchy, red, swelling, bumps. There are about 2,700 different species of mosquitoes, which are a part of the family, Culicidae. They feed on plant nectar, except for the females which feed off of blood. Although it is very rare, few mosquitoes carry diseases in North America, Australia, New Zealand, the UK, Scandinavia, and other temperate countries. Especially in Africa mosquitoes are important vectors of many serious illnesses and diseases. 
The body of the mosquito like most insects, are divided into three parts (Head, thorax, and abdomen). They also have a tough exoskeleton and six long legs.
The head is where all the sensors are as well as the biting apparatus. The head has two compound eyes, an antennae to sense chemicals and the mouth parts called the palpus and proboscis. Only the females have the proboscis for biting.
Chemical sensors can sense carbon dioxide and latic acid up to 100 feet away, their prey give off these gases. Certain chemicals in sweat also seems to attract mosquitos. Mosquitos have visual sensors which means that if you are wearing clothing that contrasts with your surroundings, and especially if you move with the clothing, mosquitos can zero in on you far better. To a female mosquito anything moving is alive and full of blood. They also have heat sensors enabling the finding of warm-blooded mammals and birds very easily once they get close enough.
The thorax is a segment where the two wings and six legs attach. It contains flight muscles, a compound heart, and nerve cells called ganglia and trachioles.
The abdomen is the segment that contains the digestive and excretory organs. Mosquitos also have a pair of transparent veined wings. 
The full life-cycle of the mosquito takes about a month and within that time it undergoes complete metamorphosis. There are four distinct stages of development which are; the egg, pupa, larva, and adult stages.
After drinking blood, the adult female lays a pile of 40 to 400 tiny white eggs in still water or very slow moving water. In a week the eggs hatch into larvae, which also can be called wrigglers. These breathe air through tubes which they poke above the surface of the water. The larvae eat bits of floating organic matter and eat one another too. Larvae molt four times as they grow, after the fourth molt they are called pupae. Pupae are also called tumblers and also live near the surface of the water breathing through two horn-like tubes called siphons on their backs. In the pupae stage they do not eat. Soon after a few days an adult emerges from the pupa when the skin splits, from that point on the adult only lives a few weeks. 
Mosquitoes live mostly near quiet still standing water like puddles and ponds to lay their eggs in or on the water. They usually bite after the Sun has gone down, but there are also other kinds that will bite during the day. The female, which are the gender that bites need the blood for the energy and protein for the development of the eggs.
Mosquitoes are parasites which feed off people, mammals, birds, reptiles, and amphibians' blood. The male mosquito does not feed on blood but on plant nectar, and lives only a short time after mating. Mosquitoes travel and move by flying with their one pair of membranous wings.