A Rare Fruit Fly From Down Under Turns Up

It may have arrived with a tourist, but the discovery here this week of a single Queensland fruit fly has state and county agricultural officials bracing for the worst.

Workers quickly mobilized to distribute 200 new traps, designed to give early warning of the fly, which is the main pest devastating fruit and vegetable crops in Australia.

A trap in Laguna Beach this week produced only the second Queensland fruit fly ever found in the United States, officials said.

“This is a first for us,” said Nick Nisson, a county entomologist. “Hopefully, it’s just an isolated fly, but we need to know if there are any more out there.”

Because of its rarity, state and county officials are treating the Queensland as a scientific find, as well as a possible threat to the agricultural industry. Only one other Queensland has ever been documented as having been found in the state, in the city of La Mesa near San Diego in 1985, according to Brian Taylor, an entomologist with the state Department of Food and Agriculture who is supervising the trapping.

“We routinely identify fly problems,” Taylor said. “But this is different because it’s a Queensland.”

The Queensland is slightly larger than an average housefly and is considerably more rare than a Mediterranean fruit fly, Nisson said.

“One thing different from a Medfly is that the Queensland is not established in Florida or anywhere in the U.S., not even Hawaii,” he said. “That means it must have come in from another country.”

The Queensland is considered “the major pest to fruits and vegetables in its home country of Australia,” Nisson noted. By laying its eggs just underneath the soft outer skin, the Queensland fruit fly has been devastating not only to the citrus industry but to kiwis, mangoes and vegetables in that country, he said.

The trapped fly probably came from Tahiti, the closest area where the Queenslands are known to breed, Taylor said.

“Most likely a tourist or a honeymooner has illegally brought in a piece of fruit, found a maggot inside and threw it into the garbage,” he said. “This guy managed to survive, and we hope it’s an isolated incident.”

Local growers expressed concern and frustration that after extensive spraying last year to control the Mediterranean fruit fly, people are not more careful about bringing produce into the country.

“Any type of find like this definitely gives us concern from the outset,” said Alan Reynolds, the orchard manager of Treasure Farms, a major grower on the Irvine Ranch. “It’s additionally of concern that after all that public outcry over the Medfly, people are not more careful. People don’t want us to take eradication measures, yet then these things happen. This is something we all have to work on.”

Specialists said that eradication measures are not considered necessary for an outbreak of Queensland fruit flies. Instead, male Queenslands are relatively easily trapped, experts say.

“The male fly will feed upon the lure, which contains a chemical that is necessary for the male fly to produce its pheromones, the chemicals given off by an animal to attract the opposite sex,” Taylor said. “It’s like musk and has that sort of stimulation.”

Some traps are being set for male and female flies but many more for males, which seem more easily lured, Taylor said.

The male found Monday was initially identified by local entomologists and then flown to Sacramento for positive identification. The fly was dead when it was found in the trap and could have been there for two weeks, which was the last time the trap had been inspected, Taylor said.

The Queensland no doubt arrived here by airplane, a vehicle that is presenting more and more problems for entomologists attempting to seal this country’s borders, said a spokesman from the UC Riverside agricultural department.

“The exclusion of pests is becoming a very difficult thing,” said John D. Fox. “Planes are flying into the country from every which way every day, and flights are shorter. Planes then sit on the ground, out in the open, and anything can fly in the door.”

Queensland Fruit Fly Description: Mottled orangish-brown, housefly-sized fruit fly with pale yellow band around abdomen. Wings are transparent with dark narrow band on wing margins. Indigenous to Australia and the South Pacific islands. Diet: More than 100 types of soft-flesh fruits and vegetables, including citrus, plums, peaches and tomatoes. Eggs: Female pierces skin of fruit or vegetable and lays up to 20 eggs inside. After less than two weeks, the eggs hatch into maggots and feed on the flesh, causing rotting and crop destruction. Reputation: Considered the major fruit fly pest of Australia. To Report Unusual Findings: Place the infested fruit or vegetable inside a plastic bag or a jar; take sample to county agricultural office. Never throw out infested fruits or vegetables. Source: County Agricultural Commissioner’s Department Researched by April Jackson / Los Angeles Times