There are estimates of the number of mosquito eggs in a floodwater habitat between 0.7 and 1.3 million eggs per acre. Yes-per acre. If only a small percentage of those eggs hatched and survived to the adult stage, the number of adult mosquitoes flying around looking for blood at one time is almost incomprehensible.
http://mosquito.ifas.ufl.edu/Mosquito_Habitats.htm
Check your yard for standing water. Mosquitoes need water to reproduce. They lay their eggs either directly in water or on the dry vegetation in and around areas where, after a rain event, water accumulates.
http://www.evansville.in.gov/index.aspx?page=1483
FloodWater Mosquitoes. Many people associate mosquitoes strictly with standing water, with the belief that mosquitoes must have water to lay their eggs. The fact is, mosquito eggs need water to HATCH-but some species lay their eggs in moist soil (not standing water) and the eggs need to dry out before they can hatch. These mosquitoes are the floodwater species.
http://mosquito.ifas.ufl.edu/Mosquito_Habitats.htm
A. Female mosquitoes bite people and animals because they need the protein found in blood to help develop their eggs. Mosquitoes are attracted to people by skin odors and carbon dioxide from breath. The active ingredients in repellents make the person unattractive for feeding. Repellents do not kill mosquitoes.
http://www.evansville.in.gov/index.aspx?page=1483
Waiting for Water. Mosquitoes of the genus Aedes lay their eggs on soil where the eggs wait like seeds, until spring rain washes them into shallow puddles or pools, or wet weather causes ponds to flood and rise to reach them.
http://www.mosquitoreviews.com/mosquito-eggs.html
permanent Water Mosquitoes. Mosquitoes that are not in the floodwater group lay their eggs on standing water. A difference between the two groups is that mosquito eggs in this category can not withstand drying out.
http://mosquito.ifas.ufl.edu/Mosquito_Habitats.htm
Mosquitoes lay eggs which hatch into larvae or wrigglers that live for a while in water, then emerge as new adult mosquitoes. Though mosquitoes live on land, they've evolved three different ways to get their eggs in the water, so the larvae can hatch where they need to be.
http://www.mosquitoreviews.com/mosquito-eggs.html
Each of the scattered eggs rests on the surface of the water like a tiny boat, because it has a float attached on either side. This page from the CDC, which describes the life cycle of the malaria mosquito, has a good drawing of the eggs and their floats. Anopheles mosquito eggs.
http://www.mosquitoreviews.com/mosquito-eggs.html
Aedes mosquito eggs. Winter Eggs and Summer Eggs. There are a few kinds of mosquitoes, like Anopheles walkeri, which lay two kinds of eggs, ones that hatch quickly in the summer, and special winter eggs that they lay in the fall.
http://www.mosquitoreviews.com/mosquito-eggs.html
Mosquitoes that spend the winter as eggs develop into adults within two weeks after hatching in the spring. The adult males survive on nectar and similar foods, since they don't need the nutrition that comes from blood, like females do.
http://www.mosquitoreviews.com/mosquito-lifespan.html
what is the nutrient in blood that helps mosquitoes develop their eggs
The nutrient in blood that helps mosquitoes develop their eggs is protein.