Imagine you are a mosquito, the feminine variety, and your customary three-day fast is over.

Bottom line: You wanna suck blood.

What about that dog? Nah, the mutt’s smell does nothing for you. That kid on the patio? Might be good, but a breeze just stole his scent.

Whoa, check out the lady across the street. Now we’re talking.

Weeding the garden on a sultry day, she is working up a lather- even 75 feet away, an easy sniff. Best of all, she’s not wearing socks. Oh, baby, there’s something special about those stinky feet.

It is true, scientists say, that when it comes to picking food, mosquitoes find some poor souls especially delectable.

”Smell is really everything,” said Laurence Zwiebel, a Vanderbilt University molecular biologist this week.

Evolution has spawned a diverse population of skeeters, spanning several hundred species and every continent except Antarctica. Some prefer cows. Others like birds or frogs.

But two facts are common to all. Only females bite. And highly sensitive olfactory systems- most pronounced in the antenna- are used to sniff out targets long before a skeeter lands.

Science is working vigorously to understand this miraculous smelling system. Short-circuiting mosquitoes’ prime navigational system might prevent millions of malaria deaths each year, as well as cases of West Nile virus, yellow fever, and other mosquito-borne diseases.

It might also bring relief to those unfortunate folks who emit the body-odor blends that make hungry mosquitoes go berserk.

Zwiebel and collaborators recently identified a mosquito “receptor” that smells a chemical in human sweat. The discovery came when they placed a mosquito gene into a fruit fly cell; the cell went nuts when it was exposed to the human sweat chemical.

That experiment gives scientists a strategy for exploring how mosquitoes might behave when they run across some of the hundreds of other smells that humans emit.

”The excitement now is, we have the means of finding out what odors the mosquito responds to,” said John Carlson, a Yale University molecular biologist.

Theoretically, if scientists can identify what attracts the most dangerous mosquitoes, those smells could be masked with lotions or by other means.

The quest has revealed a lot about how the nasty little blood-suckers search for food.

A female mosquito needs blood for the protein necessary to grow her eggs. She may take a few days off from feasting, but when looking for chow, she can detect a warm body from a distance of 150 feet or so.

Carbon dioxide is the primary cue. We exhale the gas, and it’s emitted from our skin. But scientists say it is one of a couple of hundred odors that emanate from humans as part of metabolism.

It’s not known which of these smells, or others emitted in perspiration, trip a mosquito’s trigger, but lactic acid and ammonia are believed to be among them.

”Undoubtedly, a blend of chemicals” is what attracts the insects, said Ring Carde, an entomologist at the University of California, Riverside.

Each species may favor a different bouquet.

As the mosquito zeroes in, she follows the “odor plume.” At close range, she may rely more on sight. Or she may sniff for a particular smell; the female of one cow-loving species, for example, knows it’s payday when she reaches a cloud of bovine burp gas.

Once a mosquito lands, she quickly goes to work. A pair of small tubes pierces the skin, pumping in saliva that counteracts a human’s natural systems to halt bleeding. At the same time, the razor-sharp proboscis pokes through and begins probing for blood-filled capillaries.

The feeding stops in a few minutes when the mosquito is full- sooner if the pest gets swatted. The welts left behind are the human immune system’s reaction to saliva proteins.