I was out for one of my evening walks a few nights ago when a bug picked me out of the whole dark street and decided we were now traveling companions. It buzzed my ear, circled to my nose, looped back to my eye, and no amount of swatting, ducking, or muttering under my breath convinced it to find someone else. It followed me for a full block. I wrote about a version of this once before — this time I wanted actual answers instead of just a good complaint.
Turns out there's a real, two-part explanation, and it's a little more personal than I expected.
The part I'd half-remembered was right: carbon dioxide really is a major long-range attractant, especially for mosquitoes. Every breath you exhale sends a plume of CO2 drifting outward, and mosquitoes are genuinely built to track it from many feet away, alongside your body heat and the particular cocktail of odors your skin gives off. You're not imagining that some people seem to get targeted more than others on a walk — individual body chemistry really does make some of us more detectable than others.
Here's the part that actually explains the face-circling, and it's less romantic than "hunting for blood." Once a small fly or gnat is already close to you, it's often not after blood at all — it's after moisture and salt. The thin film around your eyes, nose, and mouth is exactly what certain species specifically target; some are even called "face flies" for precisely this reason. Your face is, to a thirsty insect, a small, reliable, salty watering hole that happens to be attached to a person.
That also explains why swatting barely works. You're not scaring off a predator that's afraid of you — you're interrupting a bug that has already located a genuine resource and has every reason to come right back the moment your hand moves out of the way. The movement and rush of air from a swat can confuse its flight path for a second or two, but it doesn't register as a threat the way it would to, say, a bird eyeing a nervous rabbit.
So the bug wasn't stubborn, and it definitely wasn't personal in the way it felt at 9 p.m. on a dark sidewalk. It had simply found the most convenient source of moisture in a two-mile radius, and I was carrying it around on my own face the whole time.