They’re yellow light bulbs. You’ve probably seen them. Maybe some of your neighbors have them, or you’ve seen them on the shelf at a store. The most common ones are standard A19 60-watt bulbs with a medium (E26) screw base. They can be used anywhere a regular bulb can be used. The only difference is that when you turn them on, you get yellow light instead of white light.
You may have noticed that you see more of them in the summer and that the most common place to see one is in a porch light.
But why is that? What’s the point? Why do some people do that?
What It Does
What that yellow light does is cut down on the number of flying insects flying around it or hanging on the wall under it or the screen in your screen door. Ever noticed how many of those you have when you have a regular light bulb in your porch light?
Does It Work?
In a word, yes. Installing a yellow light bulb in your porch light, or in any outdoor fixture, will cut down the number of insects around it so much that you may think it’s totally eliminated them. It hasn’t. You’ll still have bugs, and they’ll still check it out. The difference is that they’ll then go on their way instead of hanging around.
Here’s a quick story to show the effectiveness of changing to yellow light: We’d broken the globe on one of our camping lanterns. Replacements were available in either clear glass, which it originally had, or amber glass, which was specifically intended to reduce the number of insects swarming around it.
Since we knew how effective the yellow light bulbs were, we decided to try an amber globe. It was so effective that we replaced the globe on our second lantern as well and saved the clear globe from that one for an emergency repair.
Our two lanterns had and still have, the same gas mantles they had before.
They still burn the same fuel. The only thing that changed was the color of the globe and the light coming through it. And the swarming insects essentially disappeared.
How Does It Work?
First, some things the light doesn’t do. Yellow light doesn’t repel insects, and white light doesn’t attract them. And neither light kills insects. The light in a “bug zapper” doesn’t kill them either. They will swarm around that light, but it’s the charged mesh in front of the light that zaps them.
Beyond that, there appears to be some debate about this. The folks at eHow reference GE lighting and talk about the spectrum and wavelength and wind up saying, essentially, that flying insects can’t see the yellow light – just as you and I can’t see an infrared or ultraviolet light with our unaided eyes.
At 1000bulbs, they add in color temperature and include a very nice graph of the visible spectrum – the portion of the spectrum that’s visible to us, that is. They do a nice job of explaining how the light source works, but they don’t say why they think bugs will swarm around a white light but not around a yellow one.
They do, however, make an important point: “[N]ot all insects are the same; different bugs see slightly different wavelengths.” That, plus the fact that we’re dealing with nocturnal insects here – that is, bugs that have evolved over eons, literally, to fly and feed at night -- brings us to my preferred explanation:
Debbie Hadley, About’s expert on Insects, says the bugs are mistaking a white light for the moon, which they use to navigate a straight path. The problem is that the light bulb is close enough to touch, so it’s useless as a navigational aid over any distance.
That makes sense to me. Yes, it’s about the color, or color temperature, of the light. That’s something all of these references agree on. The result of changing the color of the light with an amber glass globe in a camping lantern also showed that.
No, it’s not that the bugs can’t see it. Maybe not all of them and maybe not as well as they can see the moon, but they can. They still come up to it, but they don’t get stuck there.
Finally, the close resemblance between a round, white light bulb and the round, white moon makes the possibility of confusing the two very real.
It’s been known to happen to humans.
They're confused by a light that resembles the moon, and not so much by one that doesn't.
OK, Where Can I Get One?
Yellow bug lights, or “Bug Away” lights, can usually be found in most hardware and home improvement stores. If that isn’t working for you, they’re available online. Compare Prices. Either way, you can find them in fluorescent, or CFL, as well as incandescent. Saves money and keeps on burning.