Bug lights are incandescent or fluorescent bulbs that have been treated with a yellow or gold coating. These bulbs don't repel insects--they simply attract them less than other types of bulbs. According to the General Electric Lighting website, flying insects are most attracted to the shorter blue and ultraviolet wavelengths of the electromagnetic spectrum. By coating bulbs in yellow and gold, those wavelengths are lost. Bug lights are available in many shapes and sizes, from standard-size incandescent to compact fluorescent and floodlights.
According to the Ace Hardware website, electronic bug killers use blue or ultraviolet light, which is not harmful to the human eye, to attract insects into an electric grid. The website says the higher the wattage of these units, the greater the luring power. High-wattage units kill and burn away bugs immediately. Lower wattage units only kill bugs, and have to be cleaned. Electronic bug killers are most effective at night, according to Ace, when they don't face interference from the sun's rays.
Two other types of bug killers also use ultraviolet light to attract insects. Drowning-type bug killers force entering insects into a pool of water through the use of fans. The water is treated with detergent so the insects cannot float and eventually drown. Sticky-tape bug killers catch insects on a replaceable sticky surface after they have been lured into the instrument through ultraviolet light.
Bug lights and bug killers need to be properly placed to be effective. Bug lights are appropriate for use near entrances to avoid steering bugs into the house. They are also effective for lighting outdoor patios, decks and eating areas. Bug killers, because they attract bugs, rather than repel them, should be placed between 25 and 50 yards of the area to be protected, Ace Hardware suggests. Bug lights and bug killers are widely available in hardware stores and over the Internet.