Is there a certain reason why mosquitos are so weightless?

I think you just stated it. Their weightlessness is part of their success strategy. If they were heavy, you’d feel it and brush them off. Also their saliva contains an anesthetic so we don’t feel the bite. Clever little buggers.

You said you can feel bugs crawling on you. I don’t think mosquitoes move much once they land. Once they touch down, they get right down to business.

They aren’t very big.

Stealth, basically they’re sneaky little bug-gers!

@worriedguy has it. Though the “strategy” was probably conceived by all the noticeable mosquitoes getting smashed.

I don’t even want to think about mosquitoes being strategical. That’s right out of a horror movie, that is.

I agree with @worriedguy.

Although, I think mosquitoes are evil and soulless ..which explains their cunning weightlessness. :P

They don’t weigh much.

They are even trickier than just being virtually weightless. They also see in the infrared region! What good is that? We all know CO2 is colorless in visible light. But, infrared light is absorbed by CO2. That means they can see a dark plume coming out of your nose and mouth as you breathe and can fly toward you even if they are not downwind.
They are a formidable enemy indeed.

I find that holding my breath doesn’t work for very long. And, yes, I’ve tried this in the past.

BREATH @PluckyDog!!!

Saves energy when they fly.

They are not weightless. They weigh about 2.5 milligrams while the largest species is said to weight up to about 10 milligrams. Male mosquitoes are slightly smaller than female mosquitoes.
Other facts

I usually feel them land on me. And when I don’t, I do feel then bite me…

Because of the success they had on Jenny Craig (literally)