How Bug Zappers Work

By: Craig Freudenrich, Ph.D.  | 
The parts of a bug zapper
Key Takeaways
  • Studies have shown that bug zappers may not be effective against mosquitoes and biting gnats, as they often attract and kill non-target insects, which can disrupt local ecosystems.
  • Alternatives to traditional bug zappers include devices that emit carbon dioxide, Octenol and moisture to attract mosquitoes, with some claiming to collapse entire mosquito populations by targeting egg-laying females.
  • Personal protection strategies against mosquitoes include eliminating standing water, using insect repellents containing DEET and utilizing citronella products, although no perfect mosquito-control device exists yet.

While you have fun outdoors, many insects get to enjoy a good meal. Either they're eating your food or they're eating you. To clear your yard of these insects, you can try a variety of devices, ranging from simple Citronella candles to elaborate traps to pesticides (such as Dursban) to electronic bug zappers. A bug zapper, more formally known as an electronic insect-control system or electrical-discharge insect-control system, lures bugs into it and kills them with electricity. In this article, we will examine the parts of a bug zapper, learn how this device works and discuss the controversies surrounding its use. We'll also look at some other bug-control devices that may make your time outdoors more pleasant.

Inside a Bug Zapper

The first bug zapper was patented in 1934 by William F. Folmer and Harrison L. Chapin (U.S. patent 1,962,439). Although there have been many improvements, mostly in the areas of safety and lures, the basic design of the bug zapper has remained the same.


Bug zappers are incredibly simple. The basic parts of the bug zapper are:

  • Housing - Exterior casing that holds the parts The housing is usually made of plastic or electrically grounded metal and may be shaped liked a lantern, a cylinder or a big rectangular cube. The housing also may have a grid design to prevent children and animals from touching the electrified grids inside the device.
  • Light bulb(s) - Fluorescent light that attracts insects, usually mercury, neon or ultraviolet (black light)
  • Wire grids or screens - Wire meshes (usually two) that surround the light bulb and are electrified to kill insects
  • Transformer - Device that electrifies the wire mesh, changing the 120-volt (V) electrical-line voltage to 2,000 V or more

­The increased voltage supplied by the transformer, at least 2,000 V, is applied across the two wire-mesh grids. These grids are separated by a tiny gap, about the size of a typical insect (a couple of millimeters). The light inside the wire-mesh network lures the insects to the device (many insects see ultraviolet light better than visible light, and are more attracted to it, because the flower patterns that attract insects are revealed in ultraviolet light).

As the bug flies toward the light, it penetrates the space between the wire-mesh grids and completes the electric circuit. High-v­oltage electric current flows through the insect and vaporizes it. You often hear a loud "ZZZZ" sound when this happens. Bug zappers can lure and kill more than 10,000 insects in a single evening. By design, bug zappers do not discriminate between types of insects, but because of their luring strategy, they tend kill those insects that are most attracted to ultraviolet light. Mosquitoes, unfortunately, are not attracted to ultraviolet light.

We'll look at bug zapper controversies and other bug zapping methods in the next section.­



Bug Zapper Controversies

Aedes aegypti mosquito

Although bug zappers have been in use for decades, studies have questioned their effectiveness.

In 1996, University of Delaware researchers Timothy Frick and Douglas Tallamy published a study in the journal Entomological News. They had collected and identified the kills from six bug zappers at various sites throughout suburban Newark, Del., during the summer of 1994. Of the nearly 14,000 insects that were electrocuted and counted, only 31 (0.22 percent) were mosquitoes and biting gnats. The largest number (6,670, or 48 percent) were midges and harmless, aquatic insects from nearby bodies of water. The researchers claimed that killing this many harmless insects would disturb nearby ecosystems. According to Tallamy, most species of mosquitoes are not attracted to ultraviolet light, and certain species only bite during the day. Tallamy claims that bug zappers are worthless for reducing biting flies, exact a heavy toll on non-target insects and are counterproductive to consumers and the ecosystem.


Other Bug-zapping Strategies

There are lots of alternative means to control insects, particularly mosquitoes. In fact, traditional electronic bug zappers may be ineffective against mosquitoes, which, as we learned in the last section, are not necessarily attracted to the ultraviolet light. Some electronic bug zappers compensate for this by emitting Octenol, a non-toxic, pesticide-free pheromone mosquito attractant.

Mosquitoes are attracted to the carbon dioxide emitted by humans in our breath and sweat, so several types of mosquito zappers try to take advantage of this. One such product emits a steady stream of carbon dioxide, Octenol attractant and moisture. Mosquitoes are attracted to this mixture, get sucked into a net, dehydrate and die. The device is powered by a propane tank, so no electricity is required. One manufacturer claims that entire mosquito populations collapse in six to eight weeks as egg-laying females are destroyed.

Another device uses a chemical that the manufacturer claims blocks the mosquito's olfactory receptors. The makers of this product say that blocking the insect's ability to "smell" carbon dioxide reduces the number of mosquito landings and bites.

Eradicating the female mosquitoes and their eggs is essential to mosquito control. Since mosquitoes lay eggs in water, you should eliminate all sources of standing water, such as watering cans or old tires. Cover any rain barrels, and if you have a pond, stock it with fish that will eat the mosquito larvae.

You can find spray-on repellents at most stores. These sprays often contain DEET.

Commercial pesticides are available that kill mosquito larvae and adults. Municipalities often spray pesticides, particularly malathion, on a large scale in the spring and summer to eliminate mosquito populations.

For personal protection, you can use a broad-spectrum insect repellant that contains N, N-diethyl-m-toluamide (DEET). DEET repels most ticks, mosquitoes and other biting pests. Be sure to read product labels for usage directions.

Another means of personal protection from biting and flying insects is citronella oil. Citronella oil is a product of several types of plants. It is an effective mosquito repellant in high concentrations, but individual plants do not make enough oil to be effective. Citronella can also be found in candles and torch oil -- both meant to be burned outside.

If you like citronella, citronella wristbands give you an easy way to protect yourself on a personal basis.

Many people erect Purple Martin birdhouses or bat houses in the hopes that these animals will eat lots of mosquitoes. While Purple Martins and bats eat huge quantities of insects, mosquitoes are not a significant portion of their diet.

So, the search for the perfect mosquito-control device continues.

For more information, check out the links on the next page.


Frequently Asked Questions

Are bug zappers safe to use around children and pets?
Bug zappers are generally safe to use around children and pets as long as they are installed out of reach. Ensure that the electrical components are secure and that the device does not become a curiosity that could lead to accidents.
Can bug zappers be used indoors?
While bug zappers are primarily designed for outdoor use, there are models that are suitable for indoor use. These typically have a containment feature for the insects and use attractants that are safe for indoor environments.