Why are there so many butterflies in Southern California?

First the Chartreuse hills. Then the purple, yellow and white wildflowers. Now, there are orange and black butterflies.

They are painted ladies, to be exact. By the millions, butterflies flutter in southern California, feasting on a proliferation of herbaceous plants such as chrysalis and hollyhock.

This is part of their normal northward movement from the barren deserts of Mexico to the lush Cascade Range in the Pacific Northwest. But the population is oversized this year, the latest natural colorful phenomenon resulting from the abundant winter rains and a cooler February that prevented the plants from drying out.

"The good rainy years, the migration is really noticeable," says Brian Brown, curator of entomology at Natural History Museum in Los Angeles County.

Brown says their move through southern California probably began about a week ago. It was then that the locals started calling the museum to report what they saw.

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The painted ladies were seen twinkling around Los Angeles, from the Walk of Fame to Beaches of South Bayand across Southern California, including in and around Palm Springs.

Doug Yanega, Senior Scientist at the Museum of Entomology Research at Riverside University, said that he and his colleagues spent their day off counting butterflies.

"We saw at least 100 a minute," he says. "It just looks out a window. We are talking about a population of several million people, no doubt.

According to Yanega, in the deserts of Southern California, there are caterpillars "everywhere".

"I know people who work in the field and say," Fuck shit, "he says.

Ian Recchio, curator of reptiles and amphibians at the Los Angeles Zoo, acknowledges that he has seen more ladies painted during his recent trips to the Mojave Desert than to Griffith Park.

"Unfortunately, I see most of them breaking against my window while I drive," he says.

It takes about one month for the larvae to develop, so if the weather does not become too hot or too dry, the high volume of butterflies could last another month or even three months, Yanega explains. "As long as there is green vegetation, then we should see them."

An adult butterfly usually lives only a few weeks. Their flight north usually consists of several generations, a butterfly moving a certain distance, then laying. Its brood will hatch and continue north.

This looks like the famous migration of monarch butterflies, which are usually mistaken for painted ladies.

Brown says that the movement of painted ladies is not as dramatic, but it is much more ubiquitous: there are ladies painted around the world.

"Migration does not just happen here in North America. This is also happening between Africa and Europe, "he said. "It's really a global phenomenon."

With precipitation 5.91 inches above normal in downtown LA since October, According to the National Weather Service, Recchio says Los Angeles should expect to see more insects this spring. "In the end, we get a lot of rain, which equates to more bugs – of all types," he says.

And that means more butterflies. According to Recchio, other types of more particular butterflies in southern California will benefit.

"Southern California is a hotspot for biodiversity," he says. "We have an incredible diversity of butterflies in this part of the world."

But these painted ladies are native and it's something to celebrate, Yanega says.

"It's one of the few times we can pop something and not feel guilty," he says. "It's cool."