Lemongrass works great for repelling mosquitoes though it is hard to really estimate a range or an effective concentration to keep the little suckers away. I found that my legs get the most attention when I'm out in the field and since it is way too hot and humid to wear long pants, I've had to just “take it” like a Thai whore, that is, until today.
Putting lemongrass in my pockets has been ineffective. Rubbing it on my skin has not shown any noticeable effect either. Sticking a clump in each boot, however, has done wonders.
Grass in the boot has been highly effective at keeping my calves bite free. To be fair, the mosquitoes might be deterred by the leaves waving around rather than the scent. At any rate, it keeps them away from my legs. I haven't gotten bit on my arms either though my upper body gets less attention with or without the lemon grass in my boot.