https://www.npr.org/sections/goatsandsoda/2020/06/14/876002404/locusts-are-a-plague-of-biblical-scope-in-2020-why-and-what-are-they-exactly
"What makes a locust a locust? According to Overson, it comes down to a superpower possessed by locusts that enables them to go through a remarkable switch in development.
Most of the time, locusts exist in their "grasshopper phase" — they lead solitary lives, they're green and pretty unremarkable.
"Nobody really notices them," Overson says.
The timing of this varies, and the shifts are pretty irregular, but for years, locusts can live like this – alone, biding their time.
But when environmental conditions are right — usually when there's a lot of rainfall and moisture — something dramatic happens: "They increase in numbers, and as they do so, they sense one another around them," says Overson.
This is what biologists call the "gregarious phase" of the locust."
