They work IF you don't get much breeze: if you get much wind, the 'skeeters
just get blown past them and they can't attract them to kill them.

Basically, they're bug zappers with a small heater-burner. The heat and CO2
attract the 'skeeters and the electrified screen electrocutes them.

The instructions tell you that it'll take at least a month for them to
become effective and longer if you have a pond nearby.

I have had a Mosquito Magnet for two full seasons and love it. They work by
creating heat by burning propane. A disposable cartridge lets off CO2.  That
creates a scent cone that attracts the bugs, so little or no breeze is the
best.

The two things attract mosquito. When they get to close, a little fan sucks
them up and deposits them in a net, where the fan keeps them until they die
from the heat. They then shrivel up. I dump out about a 1/2 cup every day or
two. That is a LOT of mosquitoes. It takes about two days to clear out my
45' x 80' back yard and the little buggers are gone all summer.

Get an extra net and a couple of cartridges as you will go through one
cartridge every few months. The extra net makes it easier to clean. You can
pop it in while you are dumping out and cleaning the old one. I go through
about 20 lbs of propane every 2.5 weeks. You do need 110VAC for the vacuum
fan.

It is best to put them in a sheltered area, away from your RV, patio or deck
as it attracts mosquitoes from all over the neighborhood. A stiff breeze
makes them useless, but a light breeze is OK. I find mine gets the most
actions late in the evening and all night. There is typically no wind in
southern Alberta during the night, but the late afternoons can be hell.

By the way, they only kill biting insects. I have never found a moth,
butterfly or a bee in the net. Guess the scent doesn't turn them on.

Wayne

I have a Mosquito Magnet and it works great - deposits lots of dead
'skeeters in the little bag (contrary to another post, it does not
electrocute them, just sucks them into a little bag). I bought it to
keep at the beach but the only problem I have is that you have to
change the propane bottle every few weeks and that doesn't necessarily
coincide with my trips to the beach. Sometimes we leave with about 1/2
bottle left and not return until it's empty. Because of that, I plan
to sell mine on eBay as soon as I get a chance and just continue to
spray.