We got one of those since June 2011 (flowtron BK-15D, 1/2 acre). It works as a charm, best killing machine ever. I forgot to put up this years but I can not go to the backyard because of the mosquitos. Daisy want to play, Bill want the back door close because of flies and mosquitos. Just found the unit in the utility room and place outside and the mosquitos and flies started to fall dead immediately. I am ordering another one to place in the front door (flowtron BK-40D 1 acre). If you live in Florida, this is a must. Personal note: Try to leave away from where your bees are. Any fly insect seems to be attract to this thing.