Bug zappers are designed to lure and kill insects. The design is simple: A transformer, light bulb and electrified wire mesh are housed in a plastic or grounded metal frame, usually in the shape of a cube or lantern. The light bulb hangs in the middle and is surrounded by two layers of wire mesh grid, separated by a tiny space of a few millimeters. Some bug zappers have a third layer of non-electrified wire mesh around the outside of the cube as a safety precaution. Most have a hook on top so you can hang them up on a porch or from a tree.
The light bulb lures insects to the bug zapper. While any florescent light bulb can be used, most bugs (although not mosquitoes) are attracted to ultraviolet light. Mercury or neon light bulbs can be used as well. As the light bulb is attracting insects, the transformer housed in the roof of the bug zapper is electrifying the wire mesh grids, boosting the standard 120-volt electricity to over 2,000 volts.
As the insect approaches the light, it fills the tiny space between the two mesh grids, which completes the electrical circuit. In an instant, the bug is vaporized. You often hear a noise that sounds like a "zap" as the insect is killed, which is how bug zappers got their name. Bug zappers can kill thousands of insects in one night. However, many of those bugs may not be nuisance bugs. In fact, a study performed by researchers Frick and Tallamy in 1996 and published in Entomological News found that nearly 48 percent of all bugs killed by a bug zapper were non-biting, harmless aquatic bugs. For this reason, some bug zapper manufacturers are starting to make bug zappers that emit Octenol, which attracts mosquitoes.