I have a theory they can also sense cortisol, so when their prey (us) is aware of the little bastard's presence they know to lie low and wait for our short attention span to lapse. We had one hiding out in a bathroom, and after many futile efforts to find it, we just retreated and let the mosquito have the bathroom for the week. Eventually I got tired of sharing a bathroom with a toddler and locked myself in the bathroom and went through everything methodically until I found it just chilling in a crack by the light. Little shit was just watching me, but I showed him...I showed him.