Officials have pointed to a relatively wet year as the cause of the invasion

Grasshoppers are raining down on Las Vegas in swarms that show up as a storm on weather radar.

According to Time, the Nevada city has been under siege by the inch-and-a-half long bugs for the past few days, with experts saying it could last for weeks. Officials have pointed to a relatively wet year as the cause.

“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,” Jeff Knight, a state entomologist with the Nevada Department of Agriculture, said at a news conference on July 25, according to CNN and Time.

“We’ll have flights [of grasshoppers] about this time of the year, migrations, and they’ll move northward,” Knight added.

Grasshoppers Las Vegas

According to U.S. Climate Data, the yearly average rainfall in Las Vegas is around 4.17 inches. CNN reported that so far, Las Vegas has seen twice as much rain in 2019 than normal. The city already measured in at 4.63 inches of rain in the past six months, according to the outlet.

Grasshoppers Las Vegas

Given the intense increase in precipitation, Knight suggested that the swarms should actually be expected.

“We have records clear from the ’60s of it happening, and I have seen it … at least four or five times in my 30-plus years,” he told CNN. “There are some special weather conditions that trigger the migration.”

With the swarms now appearing on weather radar, the National Weather Service on Friday warned residents about limited visibility.

Weather Service meteorologist Clay Morgan told The Washington Post that the radar was actually not showing all of the grasshoppers’ activity but rather a “small subset” because the radar can only read higher elevation.

Knight, however, assured residents that the grasshoppers are harmless.

“They don’t carry any diseases, they don’t bite, they’re not even one of the species that we consider a problem,” Knight said last week.

“They’re not gonna bite you. They’re not gonna sting you,” he added.

If the insects somehow end up in your vehicle, Knight advised to “pull over, open the windows, let it out.”

The entomologist also gave advice on how to limit the insects from congregating around residents’ homes, as the grasshoppers like to gather around light sources.

He told Las Vegas locals to switch out outdoor lights with orange or amber light bulbs because the grasshoppers are only attracted to white light.