Finding Elusive Fruit Fly Can Make Trapper’s Day

Raymond Smith, a county agricultural inspector, guided his pickup truck to the curb and parked across the street from a small fig tree on Pasadena’s Arden Road.

Using a long stick with a hook on one end, he plucked off a glass trap filled with a brownish liquid and poured out about 20 putrefying flies that had been floating in the goo.

“Just houseflies,” he said as he dumped out the carcasses. He got in his car and drove off to an orange tree a few blocks away on Canyon Road.

“Nothing,” he said, shaking his head.

Next stop, another fig tree. Zip.

“It can get a little demoralizing,” he said as he prepared to head for the next site. Three down, only 21 more to go.

Constant Searching

For Smith and his crew of 17 full-time fly trappers, this is the stuff that every day is made of: constant looking with few finds.

And this is the busy season.

Smith heads a team of trappers monitoring eastern Los Angeles County for the various fruit flies that pose a threat to the state’s $15.5-billion agriculture industry.

It’s a demanding job, involving fighting off neighborhood dogs, staring at scads of dead flies every day and usually finding nothing important.

So far this year, the entire team, one of three in the county, has trapped only five Oriental fruit flies in its assigned area, which is roughly everything in the county east of a line drawn between Glendale and Long Beach.

Some members of his team have never caught a fruit fly.

“A lot will do anything to get a fly,” he said. “They really want a fly.”

Serious Business

While it is exciting just finding a fly, the inspectors know their search is serious business because of the damage the insects can cause. Because one female fly can lay hundreds of eggs in its 1-month life span, quick identification is essential.

Since the discovery of two Oriental fruit flies in Hacienda Heights on Oct. 10 and one in Pasadena on Oct. 20, Smith and his crew have been out every day monitoring about 150 traps spread over 3 square miles.

So far, no new flies have been found.

Normally, there are five trap sites in every square mile of the county from Pomona to Westwood. The 16,000 sites are checked every week.

When an Oriental fruit fly is found, a 1-square mile area surrounding the find is blanketed with 20 more trapping sites, which are checked every day for at least 3 months.

An infestation only takes two flies.

After finding the flies in Hacienda Heights, workers from the state Department of Food and Agriculture immediately began what professionals call “male annihilation treatment.”

The process involves spraying trees, light poles and telephone poles with a chemical called methyleugenol that attracts male Oriental fruit flies. The lure is laced with an insecticide.

“It’s extremely effective,” Smith said. “No one gets too excited about Oriental fruit flies. We’ve pretty much got that down.”

Extreme Measures

The much-publicized Mediterranean fruit fly infestations are a different matter.

Because there is no effective sex lure for the insect, eradication depends on extreme measures, such as aerial malathion spraying or the release of sterile Medflies, said Bob Donley, deputy director of the county’s Environmental Protection Bureau.

This year, there have been no Medfly infestations in Smith’s area. But flies were found in West Los Angeles and the San Fernando Valley and aerial spraying and sterile fly releases were required.

Smith said the county’s 30 trappers all had to help monitor the Medfly in the Westside.

Trappers who had never caught a fly before were suddenly breaking records, with 25 or 30 flies.

It was like a fly trapper’s feeding frenzy.

“It’s almost like getting a trophy fish,” he said. “Everyone calls their wives and says they’re going to be working late.”

But those breakouts occur only a few times a year and normally, Smith said, the biggest problem is fighting ennui.

“You got to keep your attitude good,” he said.

Like Fishing

Smith, who has been tracking the elusive flies for a year and a half, compares the process to fishing. “You may not catch anything for a long time, but when you do, it’s great,” he said.

The routine goes on with a single-minded determination every working day and sometimes weekends and holidays. “If we found a Medfly, we’d be working Christmas day,” he said.

There are several types of flies the trappers watch for, including the guava, Mexican, Mediterranean, Oriental, peach and melon fruit flies. An African pumpkin fly was found in the county last year.

The flies do not look the same, but Smith said that bright iridescent eyes are generally a dead giveaway for a fruit fly.

Each trapper checks about 200 monitoring sites a week, and each site has two to seven traps.

Various Traps

The traps are simple but efficient.

The so-called Jackson trap, for example, is a small paper tent with a dangling swab of material inside. The material is soaked in a bright green potion made up of a sex lure and insecticide. The fly lands on the swab, dies and falls onto a sticky layer at the bottom of the tent.

The McPhail trap, another popular model, looks like a small jug with a hole at the bottom. The insects fly inside and die by drowning in a brown liquid in the bottom jug called Staley’s Insect Protein Bait.

Smith said, however, that no matter how effective the trap or how artful the trapper, there is no way to guarantee a catch.

“One of my best guys never got a fly until we went over to the Westside,” he said.

Then again, it can happen to anyone at any moment.

“One of our newest girls found one on her second week at work,” Smith said as he prepared to head off to his next site. “Everyone was amazed.”