Dave Goodward's fifth-grade science class lined up across a sunny ball field in San Bernardino earlier this week, counting -- and occasionally chasing -- orange-speckled butterflies.
"I got one! I got one!" hollered one of his students from Kimbark Elementary School, adding another catch to his class' unofficial butterfly census.
Painted lady butterflies are swarming Southern California, invading gardens and splattering windshields, thanks to the explosion of wildflowers in the local foothills and deserts, a main feeding and breeding ground for the creatures as they flutter up from Mexico.
"This could be the largest migration in history," thanks to record-breaking rains and the desert blooms they produced, said UC Riverside entomologist Greg Ballmer.
There are millions, probably tens of millions this year, said David Marriott, director of the Monarch Program in Encinitas: "It's a population explosion."
The phenomenon occurs about twice every decade, Marriott said, as the painted ladies flit in a steady stream along the Southern California coast and through the deserts and mountain passes toward the Pacific Northwest. The swarms usually disperse once they reach Santa Barbara, although some butterflies will reach Oregon and even Canada.
The orange, black and white-spotted creatures fly roughly 15 to 20 mph, said Julian P. Donahue, former curator of lepidoptera at the Natural History Museum of Los Angeles County and assistant secretary of the Lepidopterists' Society. They feed on nectar from thistles and other plants along the way -- if scrub jays or speeding Escalades don't get them first.
Ron Vanderhoff, nursery manager at Roger's Gardens in Newport Beach, said the grounds have played host to many butterflies this week.
"There's lots of flowers here for them to stop and take a snack as they continue flying," he said.
For people walking through a park or zooming down the freeway, the 2-inch-wide insects are hard to miss, especially when funneling through mountain passes.
The butterflies are a common sight in the heavily traveled Cajon Pass, where Interstate 15 snakes into the desert, but have not caused any traffic problems, said Tony Nguyen, a San Bernardino-based Highway Patrol officer."Driving down the highway, it was just hard not to hit them," said Michael Hearst, spokesman for the Orange County Vector Control District. "I had one guy complaining because butterflies were all over the radiator of his car."
Unlike monarch butterflies, which are larger and fly higher, painted ladies cruise at eye level, making them easy to spot but hard to dodge.
When meeting a violent end, the butterflies leave a yellow splatter from the stored fat they use to fly long distances. The pockets of fat are filled with Vitamin A, which gives the goo its yellow color, Ballmer said.Driving along canyon roads through Aliso Viejo over the weekend, Micare Filipcik, 27, of Mission Viejo couldn't miss the swarm.
"It was a huge flock of butterflies -- like you see birds," she said. "It was beautiful."
And if it seems the painted ladies are using state highways as a guide on their northward journey, Marriott said it's hardly a coincidence.
"Roadways that run north-south were constructed in valleys, and butterflies will go through canyons and valleys," he said. "That's why you'll see them on roads."
The butterfly migration has helped double the number of visitors to the Louis Rubidoux Nature Center and Wildlife Conservation Area on the Santa Ana River in Riverside."We have droves of them coming through," said park interpreter Sherrie Chandler of the painted ladies. "I've been here for five years, this is the most I've ever seen."
The influx of winged visitors inspired Chandler to bring back Butterfly Day to the nature center May 7, where people can stand in a tent full of just-released butterflies and feed them watermelon by hand.
Painted ladies, scientifically known as Vanessa cardui, are a common butterfly found all over the world. They migrate from Mexico annually, but are most numerous in years with heavy rains, Ballmer said.
"Years where there is an abundance of host plants, they have a strong ability to increase in numbers," said Ring Carde, chairman of the UC Riverside entomology department.The insect lives about three weeks as a caterpillar and chrysalis, and about three more as a butterfly, traveling hundreds of miles and laying eggs along the way before its fragile wings give out -- or birds or lizards snap it up.
The painted lady is among roughly 165 species of butterfly native to Southern California, Ballmer said.
Experts predict another wave of painted ladies in about a month, as females lay eggs on their journey north.
The painted ladies started passing through in January, and will keep on trucking for about another month. They'll come until wildflowers such as the fiddleneck and lupine, which the larvae eat, are dried and gone, Ballmer said.
So Goodward realized he had to hurry if he wanted his elementary science students to commune with the painted ladies on their international commute before they disappear.
"There was a whole bunch, and one sat in my hand," said fifth-grader Cristina Rodarte, 11. "They're pretty."
She counted four passing butterflies Wednesday afternoon.