I wish I had purchased these years ago.  I live in Northern California among the orchards and rice fields.  There is a permanent wetlands about 1/2 mile behind me.  There are so many mosquitoes it was impossible to use my patio and yard without full strength DEET, and even then.  My horses were sometimes  driven mad by swarms of mosquitoes despite my best efforts to protect them  I purchased two of the BK 80D units.  The first week or so I was very pleased at the number of mosquitoes that met their demise--several hundred per night.  Then, on the first truly warm evening, the unit facing the wetlands was packed thickly from top to bottom with dead mosquitoes on the side facing the wetlands.  A few weeks went by with varied weather and the several hundred mosquitoes per night.  Then came the morning of May 18th.  The unit facing the wetlands was packed again top to bottom ,this time on all four sides, and I have included photos.  I am guessing the intervals have something to do with the mosquito life cycle.  The units occasionally kill a few moths and also I have seen two or three of the insects we call mosquito killers.  It also kills gnats as I have watched them fly in and get zapped.  Absolutely recommend this.  I have it set on a timer from dusk to dawn.  I can truly say these units have changed my life as I can now actually enjoy my yard and garden.