UV lights

Leptraps at aol.com Leptraps at aol.com
Thu Jun 28 11:30:54 EDT 2001

In a message dated Wed, 27 Jun 2001 10:28:46 PM Eastern Daylight Time, "JH" <jhimmel at CONNIX.COM> writes:

Hi folks - A friend mentioned to me that he has   been seeing very few moths at his lights in northern Pennsylvania. He read   on the package of his UV bulb (one of those semi-circular tubes) that they loose   their effectiveness after a while. He was wondering, half seriously, if   this was just to get people to by more bulbs. Has anyone heard of this   happening?       :::::::::::::::::::::::::::::::::
John   Himmelman
Killingworth, CT USA
jhimmel at connix.com

John:I have been designing, building, and marketing Light Traps for over 22 years. More importantly, I use the traps that I make as a Lepidopterists. As a result, I have researched the fluorescent light bulb with some GE engineers at their Neala Park Research Facility a number of years ago. Here are some of the things I learned.

Fluorescent tubes were originally design straight. The &#8220;shaped&#8221; fluorescent tubes were originally design for home/household lighting as a space saving, energy efficient and effective source of light. When UV Black Lights were developed, the pest control industry requested a shaped UV tube for their products. Bug Zappers and Insect Collection Traps for pest control is a huge market for the light bulb manufacturing industry. 

The effectiveness of bug zappers is an ongoing debate. There have been numerous studies and papers, which indicate the ineffectiveness of bug zappers, especially on the target insect, Mosquitoes. In 1999, over 6 million bug zapping devices were sold in North America. Virtually all use shaped fluorescent tubes.

The straight tube emits 99% of the light away from the bulb. Shaped tubes emit 20% of more of the light back towards some part of the tube. The &#8220;blue&#8221; bands in UV light are easily distorted. Once the light is distorted, it is virtually lost. I visited the GE Research Facility in 1985. An engineer tested a straight tube and a &#8220;U&#8221; shaped tube. The straight tube emitted a wider and longer light pattern. The &#8220;U&#8221; shaped tube emitted a smaller and extremely compact light pattern with considerable distortion. Also, as the shape tube ages with use, more and more of the light pattern becomes distorted which reduces effectiveness by 38% after 900 hours of use. This can vary greatly from tube to tube and manufacture to manufacture. The straight tube is also effected by use by 1% or less. 

The diameter of the tube also effects the amount of emitted light. The reach or the distance the effective UV light travels is extremely important in the design of the light traps. Agri-light Products produced a 15 Watt light trap for use in buildings housing live stock to collect flies and other pest insects that were attracted by the livestock. Bug zappers then replaced Argri-light traps as a matter of convenience as the Agri-light required servicing to remove the flies that were collected and killed. Bug zappers require no servicing. The bug zapper was more convenient and for a period of time it was widely believed that the flies were no longer attracted to the zappers. The &#8220;U&#8221; shape tubes in bug zappers distorted the light and had a serious impact on the effectiveness of the UV light and the performance of the device. Other chemical type products have since been developed and have replaced most bug zappers. 

I originally began with 8 Watt straight tubes, my current standard light trap is a 15 Watt straight tube. I also produce a 20 Watt straight tube. Neither the 8 Watt nor the 15 Watt can match the effectiveness of the 20 Watt.

Sylvania LTD of UK recently introduce the Quantum tube for use in the pest control industry. It has been advertised to be 40% more effective than the UV tubes currently available.  I am currently field testing two 15 Watt Quantum bulbs. The current results indicate that they have a greater reach. I intend to visit a lab in Pittsburgh, PA late this fall and have them perform a UV light test.

It is very difficult to determine moth populations with the use of a single light or type of light. Especially in urban areas where reflected light has a huge impact UV lights. Reflected light from urban areas as well as moon light greatly reduce the reach of UV light. Moon light can make manmade UV light useless.

It is my considered opinion that straight tubes are much more effective than shaped tubes.


Leroy C. Koehn
202 Redding Road
Georgetown, KY 40324


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