My yard is no longer infested by mosquitoes and I can use my pool again.  I've had my zappers for over a year now and they still effectively control the mosquito population in my south Florida yard.  What they do not tell you because they can sell more units, is that when it seems like your bulb has burned out you replace it and it still doesn't work.  Well, there is another tiny bulb under the top (get out your screwdriver) and for about $2.50 you can replace the "starter bulb" and get more years out of the zapper.  My experience is that the starter bulb (available on flowtron website) burns out faster than the u-shaped bulb that you can easily see.  Now this unit will also fry flies, lizards, and anything else that crawls or flies into it.  Follow the instructions and do NOT hang it near your door!