Mosquito ranks as the second most dangerous on our list due to the sheer amount of deaths each year (725,000 people each year.). Found in every region on the planet except Antarctica. For an average person, losing two liters of blood becomes life-threatening. The average mosquito bite drains 0.01 to 0.001 milliliters of blood. Thus it would take somewhere between 200,000 and 2 million mosquito bites to kill you from blood loss.