I have three of these (BK-80D) around my farm in Georgia that I run from dusk to dawn almost year round.  They work better than any other chemical free concoction to eradicate bugs, especially mosquitoes.  The octanol cartridge is not really necessary.  I was going to give them three stars due do durability issues, but since they work so well I bumped up the rating.  I had to replace several starter bulbs and one transformer on them.  They can easily be changed and the company will send you one if it is within the two year warranty period.  Flowtron should include at least a couple of starter-bulbs to start out with since I seem to need about two per year for the three units.  Also, the main bulbs need to be changed pretty much yearly, so consider another $30 per year for this plus the energy usage.  However, overall, and due to its effectiveness, they are the cheapest and most effective option out there to get rid of night/dusk time flying insects.