Those peski house flies crawl around and land on your food stuff in a second. I couldnt believe it the other day when I made a load of cup cakes (cooling on worktop) one dirty fly had sprinkled his happiness (black spots) all around the the top of one! yuk.
It still amazes me when I go to friends houses when I see food laid out uncovered particularly on warm days.
Living in the country I have to battle with those blue bottle flies which can do more unmentionable damage.
Those net covers are great no hastle with cling film - think I'll get a few more!