A billion painted lady butterflies swarm California skies

Painted lady butterflies pause to feed on the nectar of California's 'super bloom' during a mass migration. Photo / Getty Images

As the Californian deserts enjoy another 'super bloom' brought on by rare 'once-in-a-decade' rainfalls – the southern parts of the American State continue with their weird and wild spring awakening.

Residents of south California have been delivered another sign that winter is thawing, a big one.

A swarm of one billion painted lady butterflies have been spotted travelling across the urban areas surrounding Los Angeles.

The species, which are a close relative of the Monarch butterfly, are racing up the continent. Having spent the winter in northern Mexico they are heading to breeding grounds in Oregon.

Front row seats to the painted lady #butterflymigration! #butterflies #paintedladies #Irvine #OrangeCounty pic.twitter.com/4w55GfF8VT

— South Coast Research (@UCSouthCoast) March 12, 2019

Videos and pictures on social media have captured the winged insects midflight.
Prompted by heavy winter rains the butterfly swarms normally coincide with desert blooms said prof. Arthur Shapiro.

"Years of tremendous wildflower blooms typically are really big painted lady years," the last one in 2005 lead to an estimated billion butterflies migrating over California, said the professor who works for the University of California's College of Biological Sciences.

Southern California friends: I just sat on the beach in the South Bay for two hours while 1,000s of butterflies flew around and past me. What kind are they? What is happening? #butterflies pic.twitter.com/n1IrEaBy0D

— jessica (is not cake). (@loveheylola) March 11, 2019

Having received six times the annual rainfall in the past month, the deserts have been transformed into a wilderness garden.

South Californian students and retirees have been heading out to the meadows to see the rare sight, which normally happens one a decade.

Walked outside to find thousands and thousands of butterflies flying in a constant stream through #redondobeach. Thought it was debris in the wind at first but looks like some sort of migration. Any ideas @NHMLA ? @CBSLA pic.twitter.com/v1Zb8PH7pY

— John Schreiber (@johnschreiber) March 11, 2019

However, a second soaking hot on the heels of last year's rain is thought to have caused an even more spectacular incidence of the desert flower "super bloom."

"There's just an abundance in where it's blooming and it's coming in waves," said Betsy Knaak told AP, executive director of the Anza-Borrego Desert Natural History Association, which tracks the blooms.

California rains have brought about a rare desert wildflower bloom. Photo / AP News

The entire continent's population of painted lady butterflies migrates to northern Mexico and Texas during winter, with caterpillars normally having to make do with desert perennials such as cacti for sustenance.

The blur of orange wings might first be hard to spot. "They can pace cars at 25 miles per hour," said professor Shapiro.

The winged insects cover the 2500 miles in a single flight, so they've got to be quick.