Bright lights, bug city: Study explains why 45 million grasshoppers swarmed Las Vegas
Las Vegas is all about excess and July 2019 was no different when some 45 million grasshoppers descended on its dazzling skyline, a horde of insects that appeared on weather radar like a thunderstorm.
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Grasshoppers swarm a light a few blocks off the Strip on July 26, 2019 in Las Vegas, Nevada.
Now, new research published in Biology Letters sheds light on the insect invasion. Rather than a biblical plague visited upon the city of sin in the Nevada desert, scientists see a convergence of more common phenomena.
By mapping vegetation and weather surveillance data, researchers found the insects scattered to forage for vegetation at dusk and swarmed Vegas after dark.
The study counted more grasshoppers in a single day than the city gets visitors in an entire year.
“I think that’s one of the cool aspects of this paper — to be able to quantify the number of grasshoppers in those ‘hordes’, and show that their movement is correlated with bright lights and the landscape below,” the study’s lead scientist, Elske Tielens, wrote in an email.
Footage from 2019 show teeming masses of insects painting the Vegas sky and littered throughout roads and parking lots in a deluge that lasted from June until mid-August. The radar picked up more than 45 million grasshoppers when the swarm peaked on July 27, adding up to around 30 metric tons in weight.
Interestingly, the authors found the grasshoppers congregated more around the Vegas strip, flocking to the brightest lit regions of the night sky.
Now, new research published in Biology Letters sheds light on the insect invasion. Rather than a biblical plague visited upon the city of sin in the Nevada desert, scientists see a convergence of more common phenomena.
By mapping vegetation and weather surveillance data, researchers found the insects scattered to forage for vegetation at dusk and swarmed Vegas after dark.
The study counted more grasshoppers in a single day than the city gets visitors in an entire year.
“I think that’s one of the cool aspects of this paper — to be able to quantify the number of grasshoppers in those ‘hordes’, and show that their movement is correlated with bright lights and the landscape below,” the study’s lead scientist, Elske Tielens, wrote in an email.
Footage from 2019 show teeming masses of insects painting the Vegas sky and littered throughout roads and parking lots in a deluge that lasted from June until mid-August. The radar picked up more than 45 million grasshoppers when the swarm peaked on July 27, adding up to around 30 metric tons in weight.
Interestingly, the authors found the grasshoppers congregated more around the Vegas strip, flocking to the brightest lit regions of the night sky.
The scale of this influx depends on the coming together of two things: “large grasshopper populations because of favourable conditions, wet winter and spring [with] lots of green vegetation … and the proximity of a large urban ‘light trap,’” Tielens said.
The study newly examines the effect that artificial lights at night have on the behaviour of insects at this scale. Their interactions with man-made environments could help with conserving insect diversity and managing pest species, according to the authors.
Invertebrates that are drawn to light may be “trapped” in unsuitable areas, hindering their ability to forage and mate, they write, adding certain moths drawn to light-polluted areas are known to show greater population declines.
Outbreaks of the very same pallid-winged grasshoppers were found in Arizona in the fifties, sixties and 1998, Tielens points out, including in Phoenix, Casa Grande, Tucson, and surroundings.
“It is likely this kind of event could happen again.”
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