Thousands of painted lady butterflies have descended on the Central Coast in an annual migration that has gained a significant boost from this year's weather.

The brown-orange-and-black butterflies are often mistaken for monarchs, but can be distinguished by their constantly fluttering wings, said Gillian Andrews, executive director of the Dunes Center in Guadalupe. Monarchs tend to glide with their wings still, Andrews said.

Also, painted ladies are about three inches across, smaller than monarchs, Andrews said.

Painted ladies migrate along the coast from Mexico each year on their way to Oregon, but this year's group is significantly larger due to early rains and then a bout of warm weather, Andrews said. The combination allows more eggs to be laid because it causes more host plants - on which the painted ladies lay a single egg - to blossom.

The weather also cuts down on the number of predators, Andrews said.

"It's a real population explosion and only happens two times in a decade," Andrews said. "You're going to particularly see them where there are flowers, so people are able to see them in their gardens, and when they're out driving."

Open areas, empty lots, and dunes also attract the creatures, she said.

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"If you go out, you're seeing 10 and 20 at a time," Andrews said.

The butterflies use cues such as magnetism, geography and winds to determine what direction to fly, said Kevin Cooper, a biologist for the northern half of the Los Padres National Forest. Their antennae can pick up on molecules in the air, and their compound eyes also provide a lot of information about their environment, Cooper said.

"These aren't like birds where they migrate back and forth and learn patterns," Cooper said. "It's all kind of innate. It's hard to say that they would follow landmarks."

"Birds, when they fly, they may go several generations, and so they'll follow previous birds. The butterflies haven't migrated this way before. It's kind of amazing that they make it to these places."

Though some theories suggest the sun tells the butterflies which direction to fly, the question is "one of the prevailing mysteries," said Michael Caterino, curator of entomology at the Santa Barbara Museum of Natural History.

"I think it may be just one of those things that's hard-wired genetically and they just do it," he said.

Though painted ladies abound throughout the world, this particular type likes the coastal chaparral, Andrews said. Favorite flowers include thistle, lupine, stinging nettle and mallow. The last type of flower, or more of a weed, is often found in empty lots, Andrews said.

The butterflies also are turning up splatted on vehicle windshields and grilles. Fortunately, Andrews said, the species is not endangered.

Business has increased, said Nick Canter of Central Coast Mobile Detail in Santa Maria, which makes house calls. "I don't want to say it's just the butterflies, it's a lot of insects period," Carter said, noting that many are stuck in grilles.

"Yes it's a very big increase in (customer) volume," said Les Kamery, general manager of Santa Maria Car Wash.

"With it being the first day of spring, it's almost like a light switch. Two days ago there were hardly any bugs on the cars Š I'm sure it's a really big factor because of the butterflies."

The group of painted ladies now on the Central Coast is believed to be the same that was reported in Orange County a few days ago. The butterflies can travel up to 40 mph and several hundreds of miles per day, Andrews said.

Andrews expects the butterflies to be here about a week.

The scientific name for the painted lady is Vanessa Cardui.

* Staff writer Erin Carlyle can be reached at 739-2218 or by

e-mail at ecarlyle@pulitzer.net.

April 1, 2005