Butterflies wing it in record numbers

SAN FRANCISCO — Professor Arthur Shapiro, an authority on gooey, yellow windshield splats, says it is probably safe for Californians, Nevadans and Arizonans to put away their squeegees.

"It seems to be over," said Shapiro, a professor of evolution and ecology at the University of California, Davis, who is an expert on butterflies. "One just flew by my window as I'm talking, but there are only a few stragglers."

Better known as painted lady butterflies, the butterflies have been the scourge of highways across California and much of the Southwest for a month. By some estimates, more than a billion of the butterflies have been dodging vehicles from Phoenix to Sacramento, with varying degrees of success.

"They move in one direction, regardless of the trees or cars," said Betty Cooper, an interpretive specialist at the Effie Yeaw Nature Center, in Carmichael, Calif., where the flutterers were so dense that they looked like clouds. "It's rough on them. But nature has a way of planning for these things by overpopulating in certain years."

This was one of those years. Because of record rainfall in much of the desert, where the butterflies spend their winters feasting on fiddleneck and other weeds, the spring migration has been about 1,000 times greater than normal, Shapiro said.

That means a billion butterflies took flight in California alone, he said, most of them racing north at speeds of up to 25 miles an hour while others flittered as far east as New York. One of Shapiro's former students recently reported a sighting at Stony Brook University, on Long Island.

The spectacle has excited scientists and bug enthusiasts, and drawn elementary school classes into open fields to watch the colorful procession. Most people, though, have come to know the migration only because of the fatty deposits the butterflies store for the trip.

"While they have a stash of fat, they don't have to stop to feed," Shapiro said. "They migrate single-mindedly until they run out of fat or into your car."

Like most fat, the butterfly variety has a knack for sticking to things. The scene recently outside a Starbucks in Primm, Nev., a popular gambling layover in the Mojave Desert, was a case in point.

Many of the cars looked as if they had been spattered with raw eggs. Commandeering squeegees from an adjoining service station, drivers patiently took turns downing lattes while scrubbing their windshields, headlights, and grilles.