MONTEREY, Calif. -- It started with a retired entomology professor checking the bug trap in his backyard.
Now airplanes are swooping over the Monterey Peninsula for three nights, spraying 60 square miles of neighborhoods and farms with a substance that triggers gender confusion in a destructive species of moth.
Spraying is also set for Santa Cruz County, and, if necessary, could later be used elsewhere.
State officials call it a "biological emergency," and say the spray is the safest, most efficient way to keep the voracious light brown apple moth from devouring California's crops. But many local officials and residents see it as an assault on their health and on an environment famed for its tide pools and migrating monarch butterflies.
Despite opposition from the Monterey Bay National Marine Sanctuary and officials in Monterey, Pacific Grove and other cities, nightly spraying started Sunday and was expected to continue through tonight.
For weeks, authorities have assured residents that the spray poses no threat to them, their children, their pets, the paint on their cars or the fish in the ocean. Even the moths survive -- though the males, driven mad with desire by biological agents called pheromones, are unable to distinguish female moths from, say, neutered poodles, and their colonies wither away.
Critics of the spraying plan, backed by the U.S. Department of Agriculture, have been unswayed.
At a hardware store in Seaside, next to Monterey, Joni Hoffman was fuming as she picked out tarps to throw over her vegetable garden -- a measure officials describe as unnecessary.
"The thing that upset me most was how paternalistic it was," said Hoffman, a nurse practitioner. "It was like, `Well, thanks for living in a democracy but we don't really care what you think.' "
Some families were keeping pets indoors, throwing plastic sheets over windows, even leaving town. At schools and parks, workers were set to hose down water fountains and playground equipment. A farmers market tonight planned to shut early so people could get indoors before the planes flew.
The upset had overtones of the Medfly eradication in the 1980s and early 1990s, when planes sprayed Southern California with the pesticide Malathion in an effort to destroy the Mediterranean fruit fly. But agriculture officials said there was no comparison between Malathion and the moth "mating disruption materials."
"Next to Malathion, this stuff is like drinking water," said USDA spokesman Larry Hawkins.
As a low-flying plane released its imperceptible mist over a dark field outside Marina, A.G. Kawamura, secretary of California's Department of Food and Agriculture, said, "This is a technology that should be celebrated, not criticized."
Pacific Grove Mayor Dan Cort last week sent Gov. Arnold Schwarzenegger an unsuccessful plea for a delay, contending that state officials had not answered basic safety questions or given communities time to do research. "It's not like Agent Orange," he said, "but to many people the idea of overhead spraying is anathema. This substance has never been sprayed over an urban area before."
At issue is Epiphyas postvittana, a drab-looking, roughly thumbnail-sized moth that has caused widespread damage in Australia, New Zealand, the United Kingdom and, to a lesser degree, Hawaii. The moths had never been detected on the mainland U.S. until Jerry Powell, a 74-year-old professor emeritus of entomology at Berkeley, found two of them last year in his yard.
Although he's a lepidopterist -- a specialist in moths and butterflies -- Powell wasn't certain what he had discovered. However, he suspected the worst. He sent remains to Australia, and seven months ago received confirmation.
Unlike most other moths, the light brown apple moth has a wide-ranging appetite, indulging in some 250 fruits, vegetables, nursery plants and trees. It's a pest that the U.S. has been vigilant about, rejecting tons of Australian oranges in the 1980s.
State and federal agriculture officials took Powell's find very seriously. Since February, the state Department of Food and Agriculture has scoured the state, setting out more than 40,000 traps. So far, 7,744 moths have been found in 11 counties, mostly in the north, although one was trapped in Sherman Oaks. In March, a state-convened panel of international experts recommended the aerial drops of pheromones.
"This moth is a significant threat to the environment and the food supply," said Steve Lyle, a spokesman for the California Department of Food and Agriculture.
Santa Cruz County seems to be the seat of the infestation, with more than 82% of the moths found there. Although Monterey County only has about 6%, officials say they are boxing in the Santa Cruz moths, giving them no room to roam.
In most other places, the battle is waged with pheromone-soaked twist-ties looped around plants and branches. But the numbers are too high and the area too great for that to work on the Monterey Peninsula, said state officials.