A blue-green blob beelining for North Carolina on National Weather Service radars caused a bit of a conundrum for forecasters this week.
The culprit? Possibly high-soaring dragonflies migrating south for the winter.
As Wakefield meteorologist Mike Montefusco told The Virginian-Pilot, it’s a “running theory” after a similar case of migrating insects was reported over Ohio.
“They migrate in fall, usually prior to cooler weather arriving, and towards areas where more precipitation has fallen recently,” the National Weather Service in Wakefield, Virginia, tweeted Monday. “That said, not sure DFs can fly that high or if they move in numbers great enough to produce these returns.”
Meteorologists caught some of the insect swarms above 10,000 feet — seemingly high for the delicate creatures.
But Sally Entrekin, an aquatic entomologist at Virginia Tech, said they could be taking advantage of winds shifting south, the Virginian-Pilot reported.
“If they’re up that high, they’re on the move,” she said, according to the newspaper — likely on the lookout for a warmer places to lay eggs.
Several species of dragonfly, most often the Common Green Darners, migrate during the late summer and early fall, CNN reported.
Spreading out as they nudge southward, the media outlet reported dragonflies will travel en masse “when the conditions are right.”
One entomologist fascinated by the movement of dragonflies started collecting data on it in 2010, creating what became the Dragonfly Swarm Project.
Researchers know that dragonflies swarm, according to Chris Goforth, who created the project.
“However, these swarms are very difficult to study because they are incredibly ephemeral events,” she said on her blog. “You have to be in the right place at the right time to see one and many people will go their entire lives without ever witnessing a swarm.”
Dragonflies are an enigma in other ways, too, according to the Smithsonian. They spend most of their lives in water before reaching adulthood, which only lasts anywhere from a few weeks to a year.
They’re also “expert fliers” with exceptional vision — most of a dragonfly’s head is made up of its eyes, meaning they can see from almost every angle (except what’s directly behind them).
Perhaps most helpful for those enraged by mosquitos: dragonflies are “a great control on the mosquito population,” the Smithsonian said.
The flock of dragonflies headed for North Carolina isn’t the first seemingly bizarre blip on the radar this year.
Before that, it was ladybugs.
A bloom of the lucky bugs swarmed San Diego in June, the Bee reported, flying between 5,000 and 9,000 feet.