Why are flies so thick? I’m almost grateful that its this time of year where I’m not opening my windows so often. They manage to find their way into your house and then bang themselves repeatedly against an open window to try and get out, or just buzz around your head. I flick them gently in the right direction of the window in my humanitarian moment of not wishing to destroy a life, but I am so tempted to get the spray out! Is there any point to them other than annoy me??