A swarm of gnats can easily ruin a relaxing summer evening in the backyard. The buzzing insects are attracted to carbon dioxide, which humans continually exhale. In no time, an entire swarm can be buzzing around your head. Fortunately you can rid yourself of a gnat infestation using common household materials. First poison or drown them with bait, then try freezing them stiff in mid-flight.
Mix equal parts of vinegar with hand soap and set outside in a dish, near your yard's usual gnat stomping ground. The gnats will be attracted to the mixture, ultimately drowning in the sticky liquid.
Mix wine with a few ounces of sugar as an alternative to the soap-and-vinegar concoction. Cover the bowl with a sheet of plastic wrap and puncture holes in it to admit the insects.
Keep a bottle of hair spray handy when you go outside. If approached by the less-populous but still persistent gnat hordes, spray them thoroughly. The hair spray will stick to their wings, solidify and paralyze them, causing the gnats to fall helplessly to the ground.