Though the above nodes capture the essence of the bug zapper, I was surprised to note that neither give technical details on the workings of these technological marvels (or, as we may learn, worthless and even detrimental pieces of technology).
Bug zappers were created in 1934 by William F. Folmer and Harrison L. Chapin. Since then, little has changed in the fundamental design of the zapper. The bug zapper is usually shaped like a lantern, with an electrically grounded housing and, as speedo notes, is surrounded by a wire mesh that prevents children or squirrels from being subjected to electrocution. A fluorescent light, often of the blue ultraviolet variety, attracts insects. Surrounding the light are two layers of wire mesh, separated by a gap the width of your average insect. These wire meshes are electrified by a transformer that ups the 120-volt current that powers the zapper to 2000 volts or more.
The bug, drawn to the light, attempts to move through the wire meshes, and, with the bug zapper's trademark "BZZZZZAPP!," the insect is VAPORIZED. Bug zappers can kill up to 10,000 insects per evening.
Bug zappers have a high inherent entertainment value- one can easily waste a half an hour laughing at the hapless, deluded insects as they are dispatched by the beautiful blue light. The metaphorical possibilities of this phenomenon are legion. All sounds well and good in bug zapper land...
As Michalak will probably not be surprised to learn, bug zappers have many drawbacks. They only kill insects that are attracted to the bug zapper's light, which means that mosquitoes, the perennial summer pest, are immune to the bug zapper. In 1996, a University of Delaware study found that only 0.22 percent of insects killed by zappers in several locations were mosquitoes or biting gnats. 48 percent were, in fact, harmless and even beneficial aquatic insects from nearby water sources. Killing this many beneficial insects, the researchers said, could disrupt the local ecosystem.
Though some bug zappers emit mosquito attracting pheremones such as Octenol, more effective means of insect control include the use of citronella oil, a natural mosquito repellent that can be burned in candles or tiki torches, or constructing bat houses to attract the mosquito munching mammals.
Source:
http://www.howstuffworks.com/bug-zapper.htm