This Is Why Bugs Are Attracted to Light
Learn about the weird phenomenon that has inspired many a meme.
Nothing seems to excite your average insect more than the sight of a light source—anyone who’s ever sat on their porch with the lights on at night can attest to just how frequently and willingly bugs will fly head-first into a bulb or candle. It’s such a well-known part of nature, in fact, that it’s the source of a common expression for being drawn to something—”like a moth to a flame”—and one of this year’s most popular memes involved a moth pining after a lit-up lamp.
But what is it about street lamps, porch lights, and candles that makes bugs so attracted to them?
As it turns out, this peculiar phenomenon has even entomologists stumped. And though researchers don’t know much about the exact reasoning behind why bugs are attracted to light, what they do know is that it has something to do with phototaxis, or the physical response of an organism to light.
The bugs that are most commonly associated with flying into porch lamps—like moths and flies—are positively phototactic, meaning that they are attracted to light and tend to flock toward it. But “some insects, like cockroaches, are negatively phototactic, and they will scurry away when the light comes on,” Mike McLean, spokesperson for the Metropolitan Mosquito Control District, explains to CBS Minnesota.
Traditionally, positively phototactic insects use natural light sources like the stars, the sun, and the moon to help them navigate. However, when a human turns on a source of artificial light, scientists believe that this confuses the bug and disrupts its navigation. “We’ve created a lot of artificial moons out there in the evening, and you can see the insects try to compensate like crazy,” says McLean.
Another explanation that some scientists use to explain the bug/light phenomenon? Those insects are hungry—and misguided. Since certain flowers naturally give off reflections of ultraviolet light, some experts believe that insects are attracted to artificial light sources because they mistake them for food sources.
And though researchers have yet to definitively determine why certain bugs are attracted to light, it’s nice to have at least some possible explanations for this strange situation. And for more animal facts, check out The 20 Weirdest Habits Animals Use to Keep Warm in Winter.
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