Blacklight "Bug Zapper" Traps 

- Don't use these traps for biting flies and mosquitoes -

Summary: Mosquito traps that utilize UV light (blacklight) attract mosquitoes as well as many other insects most of which are actually beneficial. This type of mosquito trap ("bug zapper"-type) attract and kill insects indiscriminately; in fact they kill many more beneficial insects than target insects like mosquitoes and biting flies. For this reason they are a poor choice for mosquito and biting fly control.

Jack DeAngelis, PhD
OSU Ext. Entomologist (ret.)
Blacklight traps use a bluish colored, near ultraviolet light to attract insects. Insects that are attracted to the light source are then are either trapped in some sort of container, electrocuted ("zapped") by a high voltage grid, or stuck on a sticky glue surface. "Bug zapper"-type traps always use the blacklight to draw insects to a high voltage grid where they are "zapped". Manufacturers claim that mosquitoes and other biting flies are highly attracted to these traps, but see the study cited below.

What is ultraviolet light?

Ultraviolet light is bluish to invisible, electromagnetic radiation. Near ultraviolet light appears bluish to violet in color. UV light is also the part of the light spectum that can give you a sunburn so never stare at a UV light source as this may damage your eye's retina.

Insects see ultraviolet light much better than we do and hence can respond to UV light sources that appear weak to our eyes. Lamps that produce light in the near ultraviolet (UV-A) part of the spectrum are sometimes called "blacklights".

agricultural black light trap

A "real" blacklight trap in use monitoring orchard pests. Photo by USDA/ARS.

Do blacklight "bug zapper"-type traps work for mosquitoes & biting flies?

A frequently cited study, Frick, T. B. and D. W. Tallamy. 1996. Density and diversity of nontarget insects killed by suburban electric insect traps. Entomological News. 107(2): 77-82, found that blacklight traps do a poor job of attracting biting flies like adult female mosquitoes and biting gnats, and, in fact, attracted and killed many more beneficial insect species. The traps were therefore considered to be environmentally harmful because of damage to the natural fauna.

The bottom line - don't use blacklight "bug zapper"-type traps for mosquitoes. If you must use a mosquito trap try one of the propane-fueled carbon dioxide traps since they are far more selective and won't attract as many beneficial species (see Using Propane Mosquito Traps).

Effective mosquito and biting fly control

Insect repellents are still your best first line of defense against mosquitoes and biting flies (see Using Insect Repellents for detailed information). Mosquitoes around your yard should be control by eliminating breeding sites and if the problem is severe by deploying the propane-powered traps mentioned above.

"Good" uses for ultraviolet light insect traps

In commercial agriculture "blacklight traps" (see picture above) are used to monitor certain insect pests in specific situations. Ultraviolet light traps are also widely used in food handling facilities to control house flies and similar pests. And, mosquito researchers use a trap that combines ultraviolet light with carbon dioxide and odor lures to sample adult mosquitoes.

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