Build Your Own Mercury Vapor Light Setup

Overhead light hanging on factory truss

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Entomologists and insect enthusiasts use mercury vapor lights to collect a variety of night-flying insects. Mercury vapor lights produce ultraviolet light, which has shorter wavelengths than the visible light spectrum. Although people can’t see ultraviolet light, insects can, and are attracted to UV lights. Ultraviolet light can damage your eyes, so always wear UV-protective safety goggles when operating a mercury vapor light.

In this article, you’ll learn how to assemble your own mercury vapor collecting light, and how to power your light from a car battery for use in the field (or when an outdoor power socket is not available).

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An inexpensive mercury vapor light setup.
Debbie Hadley, WILD Jersey

Entomology and science supply companies sell mercury vapor light setups, but these professional rigs are often expensive. You can assemble your own rig at a much lower cost, using materials you can purchase from your local hardware store. 

  • self-ballasted mercury vapor bulb
  • clamp light fixture with ceramic lamp socket
  • long zip ties
  • camera tripod
  • extension cord
  • white sheet
  • rope
  • UV safety glasses

Additional materials needed for use in the field (where no power outlet is available):

  • power inverter with battery clamps
  • car battery
  • car battery charger
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Mercury Vapor Light Setup Using AC Power Source

If you’ll be using your collecting light in your backyard or near an outdoor power outlet, your mercury vapor setup should cost you well under $100 (and possibly as little as $50, depending on which materials you have on hand already). This setup uses a self-ballasted mercury vapor bulb, which is significantly less expensive than the traditional mercury vapor bulb with separate ballast. Self-ballasted bulbs don’t last quite as long as those with separate ballast components, but with a bulb life of 10,000 hours, you will still be able to collect bugs for many nights. Locally, you can usually buy a self-ballasted mercury vapor bulb from your local hardware or big box store. Mercury vapor bulbs are used to keep reptiles warm, so look at herpetology or exotic pet supply websites for good deals. For insect collecting, choose a 160-200 watt mercury vapor bulb. Mercury vapor bulbs are sometimes coated; be sure to select a clear bulb with no coating. I purchased a 160-watt self-ballasted mercury vapor bulb for about $25 from an online light bulb supply company.

Next, you’ll need a light bulb socket. Mercury vapor bulbs produce a lot of heat, so it’s extremely important to use a properly rated socket. You must use a ceramic bulb socket, not a plastic one, as plastic will quickly melt when the bulb warms up. Choose a bulb socket that is rated for at least the wattage of your mercury vapor bulb, but ideally, chooses one that is rated higher. I use a clamp light, which is basically a bulb socket shrouded with a metal reflector, with a squeeze clamp that allows you to clip your light on any narrow surface. The clamp light I use is rated for 300 watts. I purchased it at my local big box store for about $15.

Finally, you’ll need a sturdy mount to hold your mercury vapor light in front of your collecting sheet. If you are collecting insects in your backyard, you might be able to clamp your light fixture to a deck railing or fence. I happened to have an old camera tripod that I no longer used for photography, so I simply clamp my light onto the camera mount of the tripod and secure it with a couple of zip ties just to be safe.

At dusk, get your mercury vapor setup ready to go. You can hang your collecting sheet over a fence, or tie a rope between two trees or fence posts, and suspend the sheet. Place your light a few feet in front of your collecting sheet, and use an extension cord (if necessary) to reach a power source. Turn your light on and wait for the insects to find it! Just be sure to wear a pair of UV-protective safety goggles when you are collecting insects around your light because you don’t want to damage your eyes.

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Mercury Vapor Light Setup Using DC Power Source

For a portable mercury vapor setup that you can use anywhere, you’ll need another way to power your light unit. Obviously, you can use a generator if you have one, but it can be difficult to transport a generator to a field location where you want to sample the insect population.

You can power your mercury vapor light from a car battery if you use an inverter to convert the current from DC to AC. Purchase an inverter that comes with clamps for connecting to the posts on a car battery, and all you’ll need to do is connect the inverter to the battery, plug the lamp socket into the inverter, and turn it on. The car battery should give you several hours of power. I had a spare car battery available to use for my mercury vapor light setup, but the battery didn’t have posts. I picked up a set of battery posts at an auto supply store for under $5, and that allowed me to clamp the inverter to the battery.

If you are using a car battery, you’ll want to have a car battery charger on hand to recharge it immediately after each use.

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Your Citation
Hadley, Debbie. "Build Your Own Mercury Vapor Light Setup." ThoughtCo, Sep. 3, 2021, Hadley, Debbie. (2021, September 3). Build Your Own Mercury Vapor Light Setup. Retrieved from Hadley, Debbie. "Build Your Own Mercury Vapor Light Setup." ThoughtCo. (accessed June 2, 2023).