I did some research to find statistics about mosquitoes. I searched 21 different sources of information and here are the results:
There are 13, 924 mosquitoes per person in the world.
They have been the number one killer of humans for a long time.
Over 700k people die every year from diseases that they transmit.
Here is an infographic with more stats and facts:
I think it is interesting that we spend $7 billion on repellents each year. I was surprised to learn that there are 110 trillion mosquitoes in the world.
The economic cost of them is about $150 billion per year.
They can sense animals to bite from 164 feet away by carbon dioxide. During a full moon they are 500 percent more active. Females live for 2-3 weeks.
They intake .001 to .01 ml of blood when they feed. The human body has about 5 liters.