I have never figured out what these pesky, filthy critters purpose is to our ecological system! They drive me crazy! Especially early in the morning when they awake before me & decide I need to awaken. Guess if we'd close our doors before sleeptime so many wouldn't choose our home as their home, but I love cool fresh air! And the old belief that screens keep all unwanted visitors out, is just that...OLD! These things can filter in however they choose!
Living with animals on the grounds around us, tend to add to the numbers in their population within my walls...I know....but what can one do!
Be irritated that's what one can do!