UV Lights

Leptraps at aol.com Leptraps at aol.com
Tue Mar 26 17:10:37 EST 2002


I recieve numerous requests almost daily for information on UV lights. Which is the most effective, UV, MV, BL, etc., etc. Many of the request come from those of you that subscribe to the same lists that I do. I am no electrical engineer. I have read enough about the how, where and what of UV to be somewhat dangerous. I am no expert. I have taken the time to explain what I know in some detail. I have gained my knowledge through experience and no more. I have used my knowledge to make extremely effective light traps.

Here what I know about UV!

I originally sent this message to in response to “Lights, Lights, Lights”, (On Insectnet.com) but I believe a new thread may be worth the effort. There have been a number of posts seeking information about Light Traps, the effectiveness of various types of UV lights and what UV lights work best. I will attempt to provide some information that may help all of you.
I have been designing, making, selling and using UV Light Traps, UV Light set-ups and fixtures for over twenty years. I am by no means an expert, but I do know enough to be dangerous. 

There have been numerous studies to determine why UV light attracts insects, none of them have ever really proven why. Using UV light to attract insects is not complicated, but it can be expensive.

Mercury Vapor bulbs are arc tube. The mercury gas is enclosed in a tube, electrical charge arcs within the tube and emits UV light. However, an unshielded bulb will emit a broad blue band. This blue band of light is what attracts the insects. Shielded bulbs (A white coating in the walls of the bulb) distort the UV effect and reduce the length or reach of the blue band. The more watts produced by an unshielded bulb increases the reach of the blue band. I use 175 watt clear MV bulbs with excellent results. The artificial light emitted by the larger 1000 watt bulbs, even shielded, can cause a sun burn effect on your skin and easily and quickly damage unprotected eyes. The best MV system available can be obtained from BioQuip Products. They offer a 175 watt MV bulb and ballast at 110 volt AC, the cost is less than $200.00. If you are handy and able to make things, a 175 watt MV home security light which cost $40.00 at Home Depot or Lowes, can be modified to suite your needs. 

Fluorescent UV bulbs produce UV light with a much shorter reach. Increasing the wattage from 15 to 40 will only increase the reach by 15%. The most effective bulbs are straight tubes. When placed in front of a white sheet or mounted in the center of the vanes on a light trap, these fluorescent tubes will emit unobstructed UV light 360 degrees. The reduced reach is the result of the length of the tube. The larger the diameter of the tube, the shorter the reach. There are actually three types of fluorescent bulbs/tubes available. A Black Light 350 (A white colored bulb)is a tube with a white coating on the inside walls of the tube. Unlike the coating on the inside of MV bulbs, the coating in a fluorescent tube enhances the blue band with minimal distortion. The Black Light Dark (A dark purple colored bulb) emits a very effective blue band, however, the coating on the inside of the tube also reduces the reach. I use both type of bulbs on my rigs. It is my opinion that the dark tube has the ability to hold insects at the sheet than a regular white UV bulb. The Sylvania Quantum Bulb in a black light bulb that emits 40% more blue bands of light (The manufactures claim, not mine) with increased reach. The Quantum bulb was developed by Sylvania for vector type traps used in the food processing and restaurant industry (This is the reason why there are no flies doing the back stroke in your soup at Applebees). I have used Quantum tubes and have found them to be very effective. I must point out that there is no real method to compare the effectiveness of a regular black light bulb and a Quantum bulb. Quantum bulbs cost slightly more that regular black light bulbs and can be purchased from pest control suppliers. Formed fluorescent tubes (Circle and “U” shaped bulbs) emitted light outward from the outer facing surfaces only. The inward facing surfaces emit light that conflicts and is distorted from light emitted from the other inward facing surfaces of the bulb. Distorted UV light is virtually ineffective. All the light traps that I design and manufacture use a straight tube. 

The use of straight UV fluorescent bulbs in conjunction with plexiglass vanes is no longer effective. Beginning in 1989, all plexiglass manufactured and sold in the USA and Canada must be UV retardant. UV light that passes through retardant plexiglass will distort the blue UV bands. 

Sun Lamps are extremely effective UV light source. They produce the strongest blue UV bands and the depth of reach is outstanding. Sun Lamps are no longer manufactured for retail sales and are no longer available in the USA. Every once in while I find a bulb or two in older hardware stores and light bulb outlets. During a recent trip to Charleston, IL, I found several (Six to be exact!) 250 watt sun lamp bulbs on the shelf in an old hardware store. The clerk said they had them for years, at $19.99 they were a real bargain. 

Several years ago I acquired a 2200 watt StarLite bulb in a round about way. These powerful UV bulbs are used by NASA and the military as a defensive measure against night vision units and thermal imaging equipment. The blue UV bands have tremendous reach but the bulb produces virtually no reflective light. Eye protection is an absolute MUST when employing StarLite bulbs.

My personal rig that I built to collect moths has the following lights:  2 – 175 watt MV, 2 – 40 watt BL. 2 – 40 watt BLB, 4 – 250 watt sun lamps and is powered by a 2400 watt Honda generator. 

All of my bucket type Light Traps are either 15 or 20 watt BL or BLB. I use yard tractor batteries or automotive batteries. 250 AMP capacity or greater. I also use several storage cell, a large battery size cell that stores power and can be completely discharges and then recharged without ever effecting the cell. They cost about $79.00 to $109.00 each. Mine are 11+ years old and still operating.

Inverters are used to operate 110 volt units from 12 volt power sources from automotive batteries and storage cells. The cost of inverters vary greatly depending on the AMP per hour usage of the 12 volt source or host. Home Depot offers a 22 AMP hour unit that will operate a 175 watt MV bulb for approximately 3 hours. The alternator must be a 40 AMP or greater to maintain the battery during the use of the inverter for this application. The more expensive units have higher source components that use less AMPS per hour and extend the use of the battery before recharging. When determining the use of an inverter, the charging source must be greater that the AMP per hour used. I have one inverter that I plug into the power port in the back of my van to operate battery chargers that recharge my batteries that operate my traps. 

If you would like more information, e-mail me at: Leptraps at aol.com


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