Do you remember the locust invasion? Now there is an explanation – St George News
ST. GEORGE – In the summer before the current pandemic, southern Utah struggled with another scourge: grasshoppers.
A locust invasion that was primarily inflicted on the Las Vegas area bled in southern Utah in the summer of 2019, peaking in July. Many residents will remember getting into their cars to see hoppers all over their windshields during the day and hovering on streetlights at night. Walking on a lawn made the creatures pop out like popcorn in hot oil.
At the time, scientists didn’t really have an answer to the insect invasion. But now a new study has a peer-reviewed theory: It was all about the light.
The study, led by the Department of Biology at the University of Oklahoma, said the reason for the locust explosion was twofold: An abundance of vegetation in the Nevada / Utah area after a wetter winter than usually late 2018 / early 2019; and the lights of Las Vegas acting as a beacon attracting grasshoppers across the deserts of the southwest like a moth in the light of a lamp.
St. George News spoke to the study’s lead author, Elske Tielens, a university insect ecologist, who said the lights of Las Vegas had flown to Mesquite and St. George.
“There was a large population of grasshoppers that year, and St. George can produce enough artificial light or sky glow to have attracted large numbers of grasshoppers as well,” Tielens said.
The researchers used radar data and determined that Las Vegas alone had around 46 million grasshoppers buzzing around the city on a night in July 2019. In a video of that data, seen with this article, the grasshopper population looks like at a large bonfire atop Sin City, the locusts appearing as flames projecting northwest – directly toward the points of light of Mesquite and St. George.
The researchers also looked at the vegetation data and correlated the strong vegetation growth in the southwest with light pollution in duo.
“This area has experienced a rainy winter and spring, which tends to result in large populations of grasshoppers. During the rainy years more eggs survive and hatch, there is more vegetation for the young grasshoppers to eat, and so you can get those large population sizes, ”Tielens said. “And that’s also a key point – that it takes both the artificial lights and the region’s large population of grasshoppers to attract these kinds of millions of people.”
Every resident is used to seeing insects – from moths to midges – swarming around their porch lights, especially in the summer. A nighttime view of the area between Las Vegas and southern Utah seen from space shows Las Vegas as a light beacon in a seemingly black sea, Mesquite and St. George looking like small, light islands to the northeast.
While the lights have not dimmed, current drought alerts show that the absence of a wet winter is likely to prevent a repeat of the locust invasion this summer.
But Tielens said that didn’t mean the 2019 takeover of the tiny creatures was a one-time event. TThe beacon of light is only getting brighter, she said, and it may take another winter in El Niño with heavy rainfall to cause another flood of locusts and insects.
“I can’t predict the future, but grasshoppers are an integral part of the ecology of western rangelands and hopefully will continue to be so in the future. The human impact on the environment by brightening the night sky will only increase, and therefore the effects of artificial light on grasshoppers and insect populations will generally continue, ”Tielens said. “Your readers probably won’t be sad to see the number of grasshoppers drop, but the long-term negative impacts of artificial urban lights on various insect species will likely become a bigger conservation issue.”
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