It’s that time of year when bugs become a big nuisance around porches, patios and outdoor dining areas. One of the most popular ways to discourage bug invasions is with a so-called “bug light,” which are yellow incandescent, CFL or LED bulbs that are marketed as being less attractive to insects. But do these lights really work?
A poster presented today at the annual meeting of AAAS (the science society that publishes the journal Science) suggests that they do. The researchers compared traps that were outfitted with six major types of light bulbs — including standard incandescent and LED versions that emit cold and warm colors as well as the yellow tinted “bug lights” — to see which attracted more or fewer insects.
The results showed that the yellow bulbs, in particular, drew significantly fewer insects than did the other types of lights. The reason? It seems that the warm color temperature of the yellow bulbs shifted the light’s wavelength outside the range of insect vision, making it less appealing.
In addition, the brightness of a bug light can confuse an insect. Bugs typically use moonlight to navigate in the dark, but when they come close to an artificial light source, it can throw off their sense of direction because it doesn’t stay at a consistent angle like the moon does. This confusion is what leads them to circle in a seemingly endless dance around the bulb.
A moth’s eyes can also get disoriented by bright light. It takes up to 30 minutes for an insect’s eyes to adjust to the darkness after coming into contact with a bright light, such as a bug light. This is why it can take so long for a moth to find a place to rest in the darkness after swooping in and out of a campfire or other light source.
Interestingly, the scientists found that although the bug light bulbs drew fewer insects overall, they still did not keep them away completely. This may be because not all bugs are attracted to the same wavelengths of light, and also because no light source is made up of a pure single wavelength.
Other options for dealing with bugs include bug zappers and the like, which are effective at killing or deterring certain kinds of insects. But this kind of device can be messy and unpleasant, as it leaves a cloud of dead bugs floating in the air.
If you’re interested in avoiding the mess and expense of these devices, try experimenting with your own DIY bug light. It’s a great way to get your kids involved in science! Wait until it gets dark, and then go outside to observe some bugs. Turn on a bright light, and then watch to see what sorts of behavior you observe. Then talk about the types of light that seemed to attract or deter the bugs, and how this might relate to the principles behind phototaxis. Be sure to share your findings with a friend or family member!