Fly-by-Night Stadium Fans : Swarms of Moths Eclipse Padres’ First Performances

Two seasons began at San Diego Jack Murphy Stadium this week. The Padres began another quest for a National League championship. And the moths opened their season with a series of swoops and divebombings that had spectators dodging more than hard-hit foul balls.

So far, the moths are off to the better start. The Padres earned their first victory in three tries against San Francisco on Wednesday afternoon, but the moths--which for years have been attracted to the stadium lights--are in the midst of what might be their most productive season in stadium history.

Although the insect, known as the white-lined sphinx, is harmless to agriculture and wildlife, its size makes it alarming to humans. With a wingspan of 3 to 4 inches, it is among the largest moths.

So Big They’re Scary

“They’re so big they scare people,” said Tom Baker, chairman of entomology at UC Riverside.

The problems at the stadium appear to be part of a sudden Southern California-wide population boom in white-lined sphinx moths, according to several regional insect experts. The moths, which usually prefer desert-like climates, have been observed in large numbers in most parts of San Diego County, even in some areas close to the coast.

Although the experts had no hard data on the increased population, all said they had noticed that the moth is more numerous and more widely distributed this spring than in the past.

“I’ve seen them flying around in the morning on the freeway, and that is quite amazing,” said Brian Harris, a lepidoptera technician at the Los Angeles County Museum of Natural History. “I haven’t seen that in a long time.”

The experts had no sure explanation for the population growth. But most speculated that it was a combination of favorable weather and the natural cycles that affect the population of the white-lined sphinx.

“They seem to run in cycles, every three or four or five years their population just explodes,” said David Faulkner, curator of entomology at the San Diego Natural History Museum.

The moths that are flying now are the result of eggs laid last summer, Faulkner said. He said the white-lined sphinx is a hardy moth

that probably was not affected seriously by the lack of winter rainfall.

That means they are here to stay, but only for another few weeks. The best news for stadium-goers and residents all the way from Mission Hills to Del Mar is that the adult moths have a life span of only four to six weeks.

“They are just going to disappear on their own,” said Kathy Williams, a biology professor at San Diego State University. “In a matter of weeks, they won’t be a problem. They’re a beautiful moth; they are just making a bad name for themselves because they were at the wrong place a the wrong time. If this happened before the baseball season, no one would have cared.”

But, because their population burst coincided with the baseball opener, stadium management is left to search for a quick cure.

“We’ve always had them, but I’ve never seen them quite like this,” said Bill Wilson, stadium manager for four years. “Everyone is complaining.”

Usually Nocturnal

Normally, day games provide a respite from the bothersome moths. But not this year. Their numbers have made the usually nocturnal creatures quite bold.

“They’re flying around like crazy now, and the lights aren’t even on,” Wilson said one afternoon from his stadium office.

The problem is so acute that a crew will spray the stadium later in the week in an effort to control the moths, Wilson said. The work will be done while the Padres are in Houston for a three-game weekend series with the Astros that starts Friday night.

Wilson said the spraying should provide relief in time for a seven-game stand starting Monday night against the Atlanta Braves.

But the Natural History Museum’s Faulkner said spraying is useless.

“That will only kill the moths that are there now,” he said. “As soon as they turn the lights back on, a new group will be drawn right back.”

Another Boom Later

Countywide, residents can expect another outbreak of the insect, probably later in the summer when the eggs laid by this group eventually develop into adult moths.

Under normal circumstances, Wilson said, he would not resort to spraying. He said swallows nesting in the stadium are usually able to keep the moths in check, but this spring the birds appear overwhelmed.

Even the hungriest of swallows, entomologist Baker said, would have a tough time controlling such a large population of adult moths.

“Those are big, big moths,” he said. “A swallow eats one of those, and he won’t have to eat again the rest of the night.”