source- www.lifehacker.com/5308039/repel-flies-with-a-bag-of-water




We've featured many , many , many different
ways to deal with mosquitoes using DIY
solutions. But what about the even more
common household fly? Turns out all you
need to deal with that is a plastic bag or
two.



Create a non-friendly environment for
mosquitoes



RickyC wrote in to tell us that he recently
visited a lakeside restaurant and noticed
some clear plastic bags filled with water
hanging from the railings. When he inquired
about the bags, a waiter explained that they
were used to repel flies.



Question-and-answer web site The Straight
Dope gives more detail on why this trick
works:


Evidently, houseflies, being highly edible
and defenseless, are nervous types, and
don't like to sit still when they see
something moving nearby, because it
could be a predator. The water bag acts a
bit like a lens—try it some time—in which
the movements of people in the area are
reflected.



Even if the fly is too far from
the action to see it directly, it can see a
shifting of light and dark in the water
bag, which it interprets as nearby
movement, and it will fly away from the
bag.



So, next time you have a fly problem, grab a
few plastic bags, fill 'em up, and let us know
how this trick works for you.