Camping and drinking are natural companions. A cold one by the fire, a bottle of wine on the campsite table, or a quick whiskey nightcap can make the great outdoors even greater. But your drink can complicate things with another natural camping companion: mosquitoes.
The evidence seems to suggest that, all other factors being equal, your outdoor beverage of choice attracts mosquitoes — especially if that beverage is beer. A 2002 study from researchers in Tokyo found that the number of mosquitoes who landed on volunteer test subjects “significantly increased after beer ingestion, compared with before ingestion, showing clearly that drinking alcohol stimulates mosquito attraction.”
The study was, however, limited to just 13 people. Other studies on the subject are surprisingly rare. Yet the results in the Tokyo study are in line with what’s known about how mosquitoes find food. The mosquitoes aren’t attracted to your drinking, it turns out. They’re attracted to what drinking does to your body.
Body heat and carbon dioxide register like a flashing “free meal” sign to mosquitoes. While core body temperature doesn’t increase after drinking, people’s skin can flush because alcohol is a vasodilator. Humans exhale carbon dioxide with every breath — the faster your exhalations, the more carbon dioxide. Carbon dioxide is also released from carbonated beer, which is why the mosquito beer trap (essentially a still-fizzy beer left open to draw in mosquitos) is a somewhat effective mosquito mitigation tool as long as the beer is away from you rather than in your hand.
While there’s a correlation between drinking and increased mosquito bites, it’s not the ethanol that’s drawing them in. Mosquitoes can’t get drunk (your intoxicated blood is far too diluted), and they aren’t attracted to ethanol as a food source. In fact, most mosquitoes aren’t attracted to the human body as a food source at all. Only pregnant mosquitoes suck your blood because they need the proteins for fertile eggs, while all other mosquitoes eat flower nectar and are important pollinators.
Your relaxing camping drink is just one of many factors involved in how many mosquitoes come after you. Studies have shown that mosquitoes prefer people with Type O blood over A, B, or AB. Men are typically more likely to be bitten as well because mosquitoes are attracted to larger bodies and their relatively larger heat and carbon dioxide output.
All this is to say that if you want a camping drink, don’t let the fear of mosquitoes keep you from enjoying. People who are likely to be bitten will be bitten regardless of whether they’re drinking or not. Just keep in mind that your open beer (or any other carbonated beverage) is a signal to pregnant mosquitoes that a potential meal is nearby.