How many mosquito bites would it take to finish all your blood?
The Sunday Nation
Nairobi,
09 November 2014
There is a war going on in Wachira Mwangi’s house. An army of mosquitoes has been making daily attacks and Wachira is thinking that he is losing. Before throwing in the towel, he’d like to know “how many mosquitoes would it take to drain a man of all his blood if they all bit him at the same time?”
This question reminds me of a story we read in high school three decades ago. I don’t remember much about it but these lines have stayed in my mind all these years: “You educated people are funny; killing a mere mosquito as if you are killing an elephant. Why, why don’t you leave the little insect alone? How much of you can it bite to make any difference to you?”
I have searched various sources via the internet and found that a mosquito sucks about five millionths of a litre of blood in a single bite. That is about 5 thousandths of a millilitre, or 0.005ml. Now that’s a minuscule amount and we can understand why some one would find it funny that educated people “kill the insect as they are killing an elephant”.
I also found that an adult human being weighing about 70kg has about 5.5 litres of blood in the body. Therefore, it would take about 1,100,000 mosquito bites (5.5L divided by 0.005ml) to drink all of it.
But Wachira’s question is not that simple. He asks “…if they all bit him at the same time?” So we must find out if 1.1 million mosquitoes can bite a man simultaneously. To do that, we need to know two things: first, the total surface area of the human body and, second, the area that a mosquito occupies while standing.
I worked out the first part of the problem many years ago (August 2004) when I was trying to calculate the amount of heat energy radiated by the human body. It came to about two square metres.
When standing on all six legs, the average mosquito occupies a rectangular area measuring about 1cm by 0.5cm. This works out to 0.5 square centimetre or 0.00005 square metre. Therefore, 1.1 million mosquitoes will need about 55 square metres to stand on together.
Clearly, then, they cannot bite you simultaneously. With your two square metres of available area, only 40,000 mosquitoes can attack at a go. It would take about 28 different attacks of 40,000 insects each to clean out your blood.
Since a mosquito takes about five to ten minutes to suck a “full-tank”, this blood sucking would last at least four and a half hours.
Of course, losing your blood to mosquitoes is the least of your worries. The greatest danger you face is that of contracting Malaria – a disease we should be more worried about than Ebola!
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