The flies are instantly deterred once the sterno gel is lit, and they will stay away as long as the gel keeps burning, which is several hours.
Keep in mind that if you have a large gathering or an 8 person table like ours, you'll need a Sterno can every few feet.
To dress it up, I removed the outside label and placed it inside a heat-safe decorative vase before lighting it.
Not only does this serve as decor for your tablescape, but it's also a great way to make sure that no one happens to bump into the can of Sterno since it gets very hot to the touch.
All Sterno cans come with tight-fitting lids that you remove before lighting the gel, but be sure to save them so that you can reuse the canned heat for other outdoor dining occasions.