^ speak of the devil, I usually use glass-cleaner (those that smells like ammonia) and use "spray" (not "stream") on most insects that's not on my bed and food 
one offset: if that fly is pregnant (usually slower and flies low), spraying that will make her lay her larve INSTANTLY!! URGH!!

one offset: if that fly is pregnant (usually slower and flies low), spraying that will make her lay her larve INSTANTLY!! URGH!!
