A pump,nozle,somthing flamable and a cigarete lighter.Put it all togeter and you get a flame thorwer.
I think bug zapers are better.Its basicly a UV bulb sorounded by a coil of wire hocked op to a voltage multiplyer runing directly on mains.Insect come bewten the wires and closes tha gap this causes a arc over and kills it.
Typical criticism of bug zappers shows that while they attract moths, gnats, etc, an evaluation of the fried bugs shows they attract almost nothing for mosquitoes.
The answer is to use a piece of meat to attract them instead of UV.
I wouldn't worry about the safety implications too much if you design a fairly low power HV power supply as you don't need much power to kill small insects, even a low power piezo ignition can kill a fly but it's harmless to humans.
If you are building it to save money. harborfreight.com has a fly swatter zapper. I bought two, they are fun. They go on sell for $2.99 all the time in the US. It works on everything I have swung it at.
you need a way to produce CO2, thats the best way to attract mosquitoes, i was reading about something on makezine.com about mixing water and brown sugar, heating it up to 40C, then adding yeast, and then you put it into a dark container, supposedly it works awesome because the yeast + sugar creates CO2, add a bug zapper to the opening, and voila!
The latest ones on sale here in Australia are a completely different design. They consist of a UV light to attract the bug, a fan to blow the bug downwards and a tray of water to drowned them. The units are about the size of a shoe box with a side cut out, the tube is mounted about an inch back from the cutout side, a cylindrical fan at the back circulates the air so it flows up one side, across the top and down the front.