We have a B&B and a farm.  We didn't want bugs on the deck while guests were out nor did we like all the flies that were in our barn this year.  We placed the unit, as directed, 25 feet from the deck and also in line with the barn door so it would pull the bugs out of it at night.  The first day we saw a lot of dead bugs.  Still, we had flies in the barn.  The next day, the unit was so full of bugs we thought it had burnt out! It hadn't.  The barn was almost cleared of flies!  By day three, we can actually stand in the yard and on our deck without being chased into the house!  Twilight is bug time, as we have ours on a dawn to dusk timer.  Once it goes on and is dark enough, the deck is virtually bug free.