An overabundance of wildflowers has attracted millions of stunning painted lady butterflies en route to the Pacific Northwest. Sightings of painted lady butterflies have been scarce in recent years, but California's rainy winter sparked a full-on Super Bloom in the desert this spring, providing the little caterpillars exactly what they needed to grow big and strong before metamorphosis.
"Heavy rain in the deserts along the U.S.-Mexico border triggers 'super blooms,' and many of the annual plants involved are larval hosts of the painted Lady," Arthur M. Shapiro, PhD, professor in the Department of Evolution and Ecology at U.C. Davis, tells me. "With abundant hosts, they can build up huge numbers very rapidly. Females lay hundreds of eggs, and their parasites and predators can't predict where and when and can't possibly catch up."
California hasn't experienced such a remarkable migration of cosmopolitan butterflies since 2005, when nearly a billion painted ladies attempted the trek. Most don't complete the journey; the offspring of the first generation usually picks up where the others left off. But thanks to the super bloom, it's a lot easier this time around, as their favorite plant is readily available.
"Painted lady butterfly caterpillars feed on thistles. When there is a lot of food available as part of a super bloom, more eggs are laid and more caterpillars survive to become adults," says Lynn Kimsey, PhD, professor of entomology in the Department of Entomology and Nematology at U.C. Davis. "This starts in the southern deserts first. Then you get these big migrations of adults moving northward, at least in part to find more food plants for their caterpillars."
For now, as they dance among the wildflowers in Southern California, it's clear the painted ladies are living their best lives.
Get a glimpse of California's historic migration of painted lady butterflies
For more sights that are truly magical, take a look at these mesmerizing pictures of the Southern Lights, then find out the best places in the world to watch the Northern Lights.
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