Science

Swarm of grasshoppers weighing 30 TONS invaded Las Vegas on one night in 2019, radar data show

Las Vegas is one of the brightest-lit cities in the US that attracts people from around the world, but the artificial lights also lured 46 million grasshoppers in one summer night in 2019.

A new study analyzed the invasion using radar data, finding that artificial light awakened the rather idle insects and did so in masses – one that weighed 30 tons.

The grasshoppers lifted up after dusk and the radar bounced off the flying swarm as it would any rain droplets and ice crystals. 

The National Oceanic and Atmospheric Administration (NOAA) picked up the scene that looked like a cloud resembling that of an intense thunderstorm.

The data also showed that the densest clouds of grasshoppers were centered over the most brightly lit parts of the city 

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The National Oceanic and Atmospheric Administration (NOAA) picked up the scene that looked like a cloud resembling that of an intense thunderstorm. Researchers used this radar to determine there were 46 million flying insects in the shot

The new details were uncovered by the University of Notre Dame and the University of Oklahoma, who set out to understand how artificial light impacts insects on a regional scale – previous works focused on a local level.

‘Using an integrated set of remote-sensing observations, we quantify the effect of a large-scale attractive sink on nocturnal flights of an outbreak insect population in Las Vegas, USA,’ reads the study published in the journal Biology Letters.

‘At the peak of the outbreak, over 45 million grasshoppers took flight across the region, with the greatest numbers concentrating over high-intensity city lighting.

In the middle of July 2019, people in Las Vegas began to notice grasshoppers filling the air at night.

The grasshoppers lifted up after dusk and the radar bounced off the flying swarm as it would any rain droplets and ice crystals

The grasshoppers lifted up after dusk and the radar bounced off the flying swarm as it would any rain droplets and ice crystals

Each day, the numbers grew, peaking on July 27 to a baffling size that locals named it “the great grasshopper invasion of 2019.”

To learn more about the night of the grasshoppers, the researchers obtained data from weather stations around Las Vegas and the

U.S. National Oceanic and Atmospheric Administration archives. They observed a cloud resembling a thunderstorm that appeared on radar screens around and over the city of Las Vegas.

They then used the data from the radar (the size and density of the clouds) and grasshopper data (their average size and weight) to calculate the number of grasshoppers that appeared that night.

Grasshoppers are seen flying around a car park

Grasshoppers are seen flying around a car park

Residents have noticed the insects along the strip and in other parts of the Nevada city, but experts claimed that people should not be alarmed by their presence

The data showed that on the peak night, the number of grasshoppers was approximately 46 million, which, the researchers note, would weigh approximately 30 tons.

It also showed that the densest clouds of grasshoppers were centered over the most brightly lit parts of the city.

Las Vegas is known for its huge, bright neon signs, which attract visitors and their money. In this instance, however, it appears the bright lights attracted the grasshoppers.

It is still not clear why the grasshoppers amassed into such numbers on that fateful night, but local weather reporters noted that the prior winter had been unusually wet.

The researchers noted that the grasshoppers appeared to arrive into the city during daylight hours, landing and settling on every available surface—it was only after the sun set and the bright lights came on that the grasshoppers took to the sky.

It is still not clear why the grasshoppers amassed into such numbers on that fateful night, but local weather reporters noted that the prior winter had been unusually wet

It is still not clear why the grasshoppers amassed into such numbers on that fateful night, but local weather reporters noted that the prior winter had been unusually wet 

They suggest that the behavior of the grasshoppers is ample evidence of the impact artificial lighting can have on insect behavior.

Jeff Knight, state entomologist with the Nevada Department of Agriculture, told CNN in 2019 that the adult pallid-winged grasshoppers are traveling north to central Nevada and are a common desert species.

He said: ‘It appears through history that when we have a wet winter or spring, these things build up often down below Laughlin and even into Arizona.

‘We’ll have flights about this time of the year, migrations, and they’ll move northward.’

He explained that the large presence of grasshoppers could be caused by the wetter-than-average winter and spring.

Las Vegas saw almost double its usual amount rainfall in the first six months of the year from January to June. Knight explained that the grasshoppers do not pose a threat as they do not carry infection or bite.


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