A bug zapper, more formally called an electrical discharge insect control system, electric insect killer or (insect) electrocutor trap, is a device that attracts and kills flying

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

s that are attracted by light. A light source attracts insects to an electrical grid, where they are

electrocuted Electrocution is death or severe injury caused by electric shock from electric current passing through the body. The word is derived from "electro" and "execution", but it is also used for accidental death. The term "electrocution" was coined ...

by touching two wires with a

high voltage High voltage electricity refers to electrical potential large enough to cause injury or damage. In certain industries, ''high voltage'' refers to voltage above a certain threshold. Equipment and conductors that carry high voltage warrant sp ...

between them. The name comes from the characteristic

onomatopoeic Onomatopoeia is the process of creating a word that phonetically imitates, resembles, or suggests the sound that it describes. Such a word itself is also called an onomatopoeia. Common onomatopoeias include animal noises such as ''oink'', ''m ...

zap sound produced when an insect is electrocuted.

History

Early model prototype fly zapper circa 1911, conceded to be too expensive to be practical In its October 1911 issue, ''

Popular Mechanics ''Popular Mechanics'' (sometimes PM or PopMech) is a magazine of popular science and technology, featuring automotive, home, outdoor, electronics, science, do-it-yourself, and technology topics. Military topics, aviation and transportation o ...

'' magazine had a piece showing a model "fly trap" that used all the elements of a modern bug zapper, including electric light and electrified grid. The design was implemented by two unnamed Denver men and was conceded to be too expensive to be of practical use. The device was , contained 5 incandescent light bulbs, and the grid was wires spaced apart with a voltage of 450 volts. Users were supposed to bait the interior with meat. According to the US Patent and Trademark Office, the first bug zapper was patented in 1932 by William M. Frost. Separately, William Brodbeck Herms (1876–1949), a professor of parasitology at the University of California, had been working on large commercial insect traps for over 20 years for the protection of California's important fruit industry. In 1934 he introduced the electronic insect killer that became the model for all future bug zappers.

Design

Bug zappers are usually housed in a protective cage of plastic or grounded metal bars to prevent people or larger animals from touching the high voltage grid. A light source is fitted inside, often a

fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet, ult ...

designed to emit both visible and

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

light, which is visible to insects and attracts a variety of them. The light is surrounded by a pair of interleaved bare wire grids or spirals. The distance between adjacent wires is typically about . A high-voltage

power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As ...

wall power Mains electricity or utility power, power grid, domestic power, and wall power, or in some parts of Canada as hydro, is a general-purpose alternating-current (AC) electric power supply. It is the form of electrical power that is delivered to ...

is used, which may be a simple

transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...

less

voltage multiplier 280px, Villard cascade voltage multiplier. A voltage multiplier is an electrical circuit that converts AC electrical power from a lower voltage to a higher DC voltage, typically using a network of capacitors and diodes. Voltage multipliers can ...

circuit made with

diode A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diod ...

s and

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of ...

s which can generate a voltage of 2 kilovolts or more. This is high enough to conduct through the body of an insect which bridges the two grids, but not high enough to spark across the air gap. Enough

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The movi ...

flows through the small body of the insect to heat it to a high temperature. The impedance of the power supply and the arrangement of the grid is such that it cannot drive a dangerous current through the body of a human. Bug-Zapper-and-a-fly

Many bug zappers are fitted with trays that collect the electrocuted insects; other models are designed to allow the debris to fall to the ground below. Some use a fan to help to trap the insect.

External traps

These traps are not effective at killing biting insects (female

mosquitoes Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small Diptera, flies within the family Culicidae (from the Latin ''culex'' meaning "gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish ...

and other insects), being much more effective at attracting and killing other harmless and beneficial insects. A study by the University of Delaware showed that over a period of 15 summer nights, 13,789 insects were killed among six devices. Of those insects killed, only 31 were biting insects. Mosquitoes are attracted to

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

and water vapor in the breath of mammals, not ultraviolet light. However, there are now bug zappers that emit carbon dioxide or use an external bait, such as octenol, to better attract biting insects into the light.

Scattering

Research has shown that when insects are

, bug zappers can spread a mist containing insect parts up to about from the device. The air around the bug zapper can become contaminated by

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

and

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's ...

that can be inhaled by, or settle on the food of people in the immediate vicinity. The

US Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

(FDA) advises that the bug zapper should not be installed above a food preparation area, and that insects should be retained within the device. Scatter-proof designs are produced for this purpose.

Hand held type

Battery powered bug zappers are manufactured, often in the shape of a tennis racket with which flying insects can be hit. Portable and rechargeable bug zappers use a lithium ion battery.

References