Passive insect eliminator. That is, it passively eliminates insects, not that it eliminates passive insects...specifically. Flying insects, mostly. *sigh*

In its essence, a bug zapper is an electrified light source. Flying insects are attracted by the light and, when they get close enough, are killed by the bug-lethal arcing of electricity. Bug zappers are mounted high above the ground and enclosed in a screen (or should be) so they don't become squirrel- or small child-zappers.

brzzzzzaappp!

The sound of a bug zapper is one of the sounds of summer. It fades into the background after a while, mixing in with the crickets, katydids and frogs. From time to time, it emerges from the cacophony with an especially loud and lengthy zapping. This indicates that some poor 'ol granddaddy of a moth or something is now taking tea with his insect Creator.

I find an ironic sort of humor in bug zappers. The bugs want to get to the light so badly. They orbit for hours, trying to find some way through the impeding screen. Then, when one occasionally reaches its goal, after all of its toil, it is obliterated. "This wonderful light is not at all what I expected!" It's kind of funny (hmmm...). Or, maybe I'm just a little sick.

One thing that I have often wondered about is how effective are these devices for the elimination of flying insects. After all the light attracts insects to kill them. So might it not produce a cloud of pests just hanging around that have not yet been killed? Though the satisfaction from the electrocution might be compensation for this in some people's minds.

I grew up in the Black Forest (not the famous one). Out near the back deck we had a bug zapper hanging from the limb of a pine tree. Hundreds of the local moths would get there, perhaps thousands. Every year the Miller Moths invade, getting into every crack they can. Hiding along the route of their migration. And thus the primary reason for the electric bug killer.

One day I was fascinated to see a blue jay perching on the side of the bug zapper. It was poking it beak into the interior space. I was sure that it was going to hurt itself, but it didn't, even when it pulled moths right off the electrified grid. Clever bird. We rarely had to clean the thing out because of it and its successors.

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...

BUT...

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.

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Source:
http://www.howstuffworks.com/bug-zapper.htm