Decades ago I had someone ask me this and I had no idea what the answer was. Periodically the question comes back to me but I’m always nowhere near a 'puter to pass it on to the SDMB. I am today.
If a mosquito bites a pimple, what happens. Does she fill up on pimple gunk and die? Does she spit it out (can mosquitoes spit?)? Does she know intuitively that there is nothing good to be had under the white bump and refuse to bite? In other words, what happens?
Silly question I know, but it’s bugged me for years.
I hate to reply to a question with little evidence, but I would assume that if they do happen to bite a pimple they would quickly be able to tell that what they were getting out of it was not blood and quickly move on to another area. It’s not like they can’t stop sucking once they start (note how if you brush your hand at one sucking blood it quickly stops and flies away before getting squashed, if you have slow reflexes, that is)
Mosquitoes can tell reasonably well what ther’re biting into so to speak. You notice how they’ll avoid some people and go for others, and once they land they’ll walk around looking for a good place to stick their little straws. I’m pretty sure they can detect different substances on the skin and smell/taste/see whether they are over a soft clean, or infected scabby area. They’d sure be able to tell once they starting sucking, at which time they’d stop. Besides that, pimples cover a tiney fraction of your skin, and are usually concentrated in places like your face that you won’t ever let a mosquito land in the first place; so unfortunately I think they do fine in avoiding trouble spots.
While it may or may not be true of females in general, it is certainly true that female mosquitos tend to be bloodsuckers. The males don’t suck; I’m not sure they even eat anything at all in their adult phase.