Yellow “bug lights” won’t chase insects away from your porch, but a switch from white lights to a yellow glow can mellow out the summer months for both you and the local insect population.
Lights drive insects crazy, fatally crazy. Anyone who has watched a moth or June beetle repeatedly slam into the base of a porch light, or swept their carcasses off the porch in the morning, knows this.
Enter the yellow “bug light,” and a lot of research over the past decade that shows yellow or amber LED lights, or switching to motion-sensor lights that pop on briefly only for security reasons, can be good for the comfort of humans and a boost for wildlife.
In his book “Nature’s Best Hope,” Douglas Tallamy warns that worldwide illumination threatens what scientists worldwide recognize are massively dwindling insect populations. Insects by the millions die nightly–drawn away from otherwise productive tasks like mating and pollinating plants, he writes. Flying insects that breed can give rise to millions of eggs and offspring, those yummy grubs and caterpillars that provide vital nutrition for young birds, and dozens of other growing critters each summer.
Several ecology studies note the critical role of lighting and insects in disturbances to wildlife, losses to agricultural systems, and increased human health risks with insects unnaturally concentrated near artificial light sources.
“Yellow/amber lights are good because they do not attract insects,” Tallamy said via email. “You could interpret that as ‘keeping insects away,’ but they don’t actually repel insects; they just don’t attract them. Every light in the U.S. has the potential to kill nocturnal insects, so even one homeowner converting to yellow lights will help.”
Marisano James, a Ph.D. candidate studying insect vision at the University of California Davis, said how insects respond to light in a specific situation might depend on the species, the type of light waves, or several other factors. That artificial lights influence insects is without question, however.
James said insects navigate by light and learned the tricks of navigating over the course of thousands of years, well before the advent of electricity.
At least one nocturnal moth species is proven to navigate by the moon, and diurnal insects take note of the sun’s position in their daily navigation.
“In a nutshell, lights confuse flying insects,” he emailed. “Insects do not have large brains, so they’re using a lot of tricks to navigate efficiently… Furthermore, those (once) well-honed tricks were apparently crafted over millennia of evolution without local bright lights. Thus, the confusion.”
James said the topic has renewed interest in recent years for several reasons. New efficient LED lights allow more control over the spectra of artificial lights. Insect populations are declining, and people are searching for solutions. Attracting insects to areas where humans gather increases the chance of people coming into contact with disease vectors worldwide.
Not just any yellow light is best, either, he said. Studies have shown that a yellow or amber LED light is easier on the bugs than old-fashion incandescent yellow bulbs.
“A yellow (or any other color) light isn’t good enough,” James said. “You want to know that the light’s spectrum is limited to the yellow (or longer) wavelength range. LEDs are typically quite good at this, but other lights are not without explicit filtration. Beware of “color temperature,” which is actually a reference to black body radiation. It refers to the dominant color of light, but by no means the only light given off by a light source of a given temperature range.”
James noted that lights aren't a cure-all, especially when it comes to pesky mosquitoes, which are attracted to people with or without nearby lights because they cue off the carbon dioxide we exhale.
