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How come, when the front door of my house is open, a fly can enter my home easily, but not escape as easily out of the same door?
Lucy Singh
Wantage, Oxfordshire, UK
My experience is that blue and green bottle flies are perfectly able to escape out of the door when they want to. I suspect they mostly just don’t fancy it – possibly because they like the still air indoors. I find that when they feel threatened, they can zoom straight through two doorways to get to the outside, even if they have spent some time bumbling against…
