We live in Tidewater Virginia, and the mosquitoes last year were terrible although the city sprayed.  The back yard was nearly unusable, and they were so numerous that many made it into the house as well.  The Flowtron unit was so effective that it was actually funny.  The first few nights, it popped nearly nonstop.  When the activity slowed, I moved it to the opposite corner of the house with a different field of view, and the nonstop popping resumed.  We still had a few mosquitoes, of course, but we weren't guaranteed a bite if we were outside for 20 minutes.  I should add here that I think the bait helped a lot, enough that I plan to continue using it even if there is a little expense involved. If you've ever been hounded by mosquitoes, you'll understand my glee when I noticed a fine, grey filament dust on a rock at the base of the unit--dead mosquitoes.  Also, this is just anecdotal, but it seemed to do an especially good job on Asian Tiger mosquitoes, the ones that raise such big itchy welts.  They disappeared after I bought this.  I know that some sources say these units don't work, but it helped us.