Flaming Out

Why are insects drawn to light?

The answer isn't easy to see.

Insects are drawn to light at night as reliably as planets orbit stars. Entomologists have exploited this by setting out light traps to collect insects and poets have used the image of a moth drawn to flame to signify self-destructive behavior.

Ecologists worry that the lure of artificial lights may help explain why insects are in global decline. But it's still unclear why insects find light so appealing.

The Harvard biologist Avalon Owens said that one prevailing theory, popular but flawed, was that insects confused porch lights for the moon or another celestial body, scrambling their sense of navigation.

Another idea is that night lights look like glimpses of daylight through a thicket of vegetation, prompting insects to try to make a beeline toward what they think is open space.

NOW there is a new possible answer.

A team led by Samuel Fabian at Imperial College London and Yash Sondhi at Florida International University say that when insects see a light at night, they believe they've found the sky's direction and try to orient themselves along an up-and-down axis.

That prompts them to roll their backs toward the light, mistakenly in cases when the illumination is on the ground, causing them to go into endless turns like a tiny airplane or to crash-land. [ Joshua Sokol ]


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