That's no moon

January 30, 2024 11:22 PM

Millennia-old mystery about insects and light at night gets a new explanation "At night in the Costa Rican cloud forest, Yash Sondhi and a small team of international scientists switched on a light and waited. Soon, insects big and small descended out of the darkness. Moths with spots like unblinking eyes on each wing. Shiny armored beetles. Flies. Once, even a praying mantis. Each did the same hypnotic, dizzying dance around the bulb as if attached to it with invisible string."
posted by dhruva (7 comments total)

Forgot to link to the paper.
posted by dhruva at 11:22 PM on January 30 [2 favorites]

Instead, they need the sky, even at night, to discern which way is “up” and cruise along, maintaining control in the air. Easy when the light source is gigantic and spread out. When it’s a concentrated bright spot? Not so much.

This explanation seems to create more problems, no? We're saying they're not 'mistaking' porch lights for the moon, the porch light is actually hijacking a response to the diffuse light of the night sky.

Okay why doesn't the moon itself do the same? Like with a moon rising, moths would tint their backs to the east, and be flying in the plane of north - south - up - down?
posted by away for regrooving at 11:43 PM on January 30 [1 favorite]

Thanks dhruva, really interesting!

My read is that the night sky is used as a reference point to maintain flight stability. Whether the moon is rising or not shouldn't make a difference as long as it is mostly fixed relative to the insect's flight. The problem is the "nearness" of the artificial light sources which cannot be relied upon to provide a fixed point. See this especially in Figure 5 of the paper.

I'd suggest taking a look at the paper instead of the article which may be providing breezy explanations.
posted by vacapinta at 3:59 AM on January 31 [6 favorites]

Excellent post title!
posted by Greg_Ace at 11:08 AM on January 31 [3 favorites]

If this ball gets rolling, maybe we'll get an update on the game this studio is working on.
posted by johnabbe at 11:11 AM on January 31

Seems like a good place to plug Ed Yong's book An Immense World. It blew my expectations away. I recall some mention of the problem of insects flying around lights, but it he must not talk about this explanation, which I guess is newer than the book. This would fit into the book perfectly.

vacapinta, I like your breezy explanation, which would have improved the article!
posted by polecat at 10:46 PM on January 31

I didn’t realize it before, but this ties together with the sea navigation issue of Constant Bearing, Decreasing Range.
posted by notoriety public at 6:03 AM on February 2