Why do mosquitoes bite some people and not others?

They’re back. After a bit of reprieve in June, the mosquitoes seem to have found their way to the backyard again — probably, that rain Fourth of July week.

So why is it that I can stand in the yard for five minutes and be consumed by mosquitoes like the way my co-workers consume a box of doughnuts and my daughter will be untouched? Why aren’t mosquitoes equal-opportunity biters?

City of Austin collects samples of mosquitoes to be tested for Zika. AUSTIN AMERICAN-STATESMAN 2016

We talked to┬áDr. Albert Gros, the chief medical officer at St. David’s South Austin Medical Center, about why that might be. Here’s what we know:

Mosquitoes love carbon dioxide, which you exhale. That’s why they like to swarm around your head. Some people might naturally exhale more C02, attracting the suckers.

Mosquitoes love hot, sweaty people. They might be attracted to certain pheromones that some people excrete more than others.

Mosquitoes also love pregnant women. It has to do with the increase in C02 you exhale when you’re pregnant, and the temperature coming off the pregnant belly. Yes, you’re pregnant and hot; yes, the mosquitoes sense that. Perhaps it’s also pheromones as well.

Clothing color might matter. Mosquitoes like people who wear dark clothing. Of course, there’s some debate about this, but why not go for lighter-colored clothing if you’re outside in summer?

Mosquitoes also like people with 0-positive blood. Lucky me.

Dr. Albert Gros

Dr. Gros’ trick is to take a daily Vitamin B complex tablet that he gets at a big box store. He’s not sure which particular part of the Vitamin B complex works, but it’s water soluble and not likely to do any harm. His theory is that it changes the way the blood smells to mosquitoes, while not being noticeable to himself or those around him. Since he started taking it, the number of bites he gets has gone down.

He also recommends spraying your body with a repellent that has DEET in it, but you don’t have to have the highest concentration of DEET to be effective. It just might mean that you will have to spray more often with the lower concentrations.

Luckily right now, Dr. Gros says, it’s been quiet when it comes to mosquito-borne illnesses such as Zika, West Nile and chikungunya.

Last year, we tested 16 repellents and found many of the best ones did contain DEET, but we also found one magic one that didn’t.