Well, I've been using these things for years now. Here's a link to the main site for these devices ->
http://www.mosquitomagnet.com/
Here's a photo of the results after only a few days when I set up my very first one:
That is a 16 ounce deli cup overflowing with dead mosquitos! I don't know how many are in there, but it's a LOT of them bloodsuckers~
In a nutshell they run off of a 20lb propane tank, which you have to replace about every 3 weeks or so. There is a fine mesh cloth net (such as in seen in the photo above) that captures the mosquitoes that are sucked up into the unit. This thing converts propane to CO2, which attracts mosquitos. It also uses a scent block which must duplicate the smell of perspiration or something, and helps increase the catch rate.
The devices work VERY well, but they aren't perfect. The propane lines will sometimes clog and have to be cleared using an adapter and a CO2 cartridge. And like everything else made by man, things will sometimes break on them. But the customer service from the company (American Biophysics) is top notch. They have GIVEN me literally thousands of dollars of replacements over the years to keep me happy. I had an older one giving me problems recently and they just sent me a newer replacement, free of charge. I didn't even have to send back the old one.
And the newer models have one feature that is literally a Godsend compared to the older models. With the older ones, you had to stand there holding the propane valve button open for about 3 minutes while the unit started and got heated up. Well, let me tell you, the reason you are using this thing in the first place is because you have a severe mosquito problem. Three minutes standing while mosquitos are buzzing all around you is VERY hard to take. The new units, however, fixed this design deficiency have a "press and run like hell" button. Just press the start button, and get the heck out of there!
Anyway, if you have a mosquito problem, these things will be the ticket to recovering your outside activities again. No joke. With more and more pathogens becoming transcontinental and transmitted via mosquitoes (West Nile virus, for example), these things could be worth their weight in gold to you. I have all three of mine running 24/7 with spare filled propane tanks lined up waiting to swap out when any one of them runs dry. Speaking of which, the secret to having fewer problems with the units is to keep them constantly running. The ONLY times I had severe problems was when the propane tank ran dry, and I waited weeks to put a new one in place. Monitor them every day and replace them immediately and you will greatly minimize your problems.
Why every propane dealer in the state of Florida doesn't sell these things as a sideline business completely boggles my mind.........