Given the option of biting anyone else or me, mosquitoes inevitably go for me even if i'm covered in repellent and surrounded by citronella candles.

Researchers at the USDA are trying to figure out what chemicals attract mosquitoes the most in order to improve mosquito repellents - Link. What with people catching West Nile, dengue fever, and malaria all over the place, it's prolly a good idea. And they really ought to speed it up. I could be next!

Mosquitoes show the best response to combinations of compounds, and it's time-consuming to find the right mix of attractants. Bernier winnowed attractants from the list of 346 chemicals by methodically mixing the skin's most abundant compounds with lactic acid. He has found that a blend of three particular chemicals attracts at least 90 percent of the mosquitoes in the olfactometer every time. ... The group has filed a patent on the blend of three compounds, which Bernier declines to identify. [Emphasis mine]

Asshole!

Although by themselves some of the blends attract more mosquitoes than Bernier's arm, if both an arm and a blend are presented at the same time, the arm wins hands down.

Figures.