Invasive Moths: To Spray or Not To Spray?

Hard to tell from the Chronicle's coverage

San Francisco, Calif. — In late June, the California Department of Food and Agriculture canceled plans to spray a pheromone that would disrupt the mating of light brown apple moths, an invasive pest that, officials say, could cause over $100 million in damage to crops.

The state would have used airplanes to spray the pheromone over densely populated parts of the San Francisco Bay area at night. “The change of course comes after thousands of citizens questioned the safety and effectiveness of the spraying program,” according to an article in The San Francisco Chronicle. One might argue, though, that paper itself played an important part in facilitating the change.

Beginning in February and throughout the spring, the Chronicle published a series of articles about complaints that the pheromone had caused health problems—such as coughing, muscle aches, and headaches—when it was sprayed over two counties south of San Francisco last fall. The articles pitted local activists and scientists, who argued that the state had not adequately studied the impact of spraying, against government officials and scientists, who insisted that the spraying was safe. Soon after its first news article on the plan, the Chronicle published an editorial stating that it wasn’t buying the government line:


The state will have to do a much better job of explaining its methods than it has so far at a handful of local meetings.

If time is critical in stamping out this pest, then Sacramento must do more to describe its plans and the foreseeable risks. The Bay Area needs convincing.


Unfortunately, the Chronicle helped impede any meaningful (and totally warranted) scientific debate about health and environmental impacts of spraying by ignoring information that was, in fact, already available. In the spring and summer of 2007, the paper published several stories about the moth’s discovery in California, including a number of pieces about a group of international scientific experts convened by the U.S. Department of Agriculture to offer advice on how to deal with the moth. (The panel, called the “technical working group,” recommended eradication.)

The state, meanwhile, had prepared several publicly available documents. One was a twenty-page report to the state legislature detailing when, why, and how it had conducted spray programs in Santa Cruz and Monterey counties. Another was a ten-page statement, from the state Department of Pesticide Regulation and the state Office of Environmental Health Hazard Assessment, that analyzed the toxicity of the pheromone sprayed in those counties and investigated health complaints following the spraying (which got a brief mention in the Chronicle’s editorial). Others included the results of environmental toxicity tests on the pheromone and the summaries of meetings of the technical working group.

What was the problem with that information? It came from the government. And as the Chronicle’s environmental reporter, Jane Kay, wrote in her first apple-moth story: “Further complicating the issue is that some residents say they simply don’t trust the government information.”

Judging by its coverage, neither did the Chronicle. After years of stories about chemical companies and bureaucrats pressuring government scientists to bend data, that’s no surprise. Indeed, right in the middle of the apple moth affair, the Chronicle published an unrelated story reporting that the Government Accountability Office, a watchdog agency, had found that “the White House’s budget office, the Pentagon and other agencies had delayed or blocked efforts by the Environmental Protection Agency to list chemicals as carcinogens by requesting more research or more time to review the risks.”

The truth about how chemicals, including pheromones and pesticides, are regulated (or unregulated, as it were) in this country is fairly scary. State officials say there’s no proof the pheromone causes harm, and they’re right. There’s also no convincing proof it doesn’t.

According to the EPA, moth pheromones have such a low toxicity that existing tests, which found that they are adequately benign, can be applied to all new varieties, even if they contain different active ingredients. But the agency doesn’t require that the inert ingredients be tested at all, or even that manufacturers list them. (The state didn’t research the inert ingredients in this particular formulation of Checkmate until ordered to do so by a judge, after they’d already been spraying for several weeks.) It also doesn’t mandate testing of the active ingredients’ potential to create long-term illnesses, even though the spray programs often lead to chronic exposure. As Kay pointed out in a number of her articles, there’s still no conclusive safety testing on the apple-moth-specific form of Checkmate used in Santa Cruz and Monterey.

“When you write that in stories people are just outraged,” Kay told me, “it’s just the first time they’re realizing that chemicals aren’t as carefully monitored as they might think.”

But there’s a difference between treating government science skeptically and ignoring it entirely. After a string fairly straightforward articles about the widespread demand for more information about its pheromone-spraying plan, Kay wrote an article headlined “Health woes is wake of pesticide spraying,” which seemed to needlessly stoke the public’s fears. Charlie Petit, who runs the Knight Science Journalism Tracker, aptly criticized the piece soon thereafter:


It is a scandal indeed that gov’t agencies legally can have squirted chemicals over a town while refusing to say what they all are.

But the epidemiology in this story isn’t. Kay leads on a family fearful their infant son’s respiratory illness was triggered by the spraying (a near simultaneous event), and understandably furious that nobody at the state seems to care. This is an old but dangerous formula in enviro writing: Something unusual occurs in the air or water or food supply. People get sick. Looks like cause and effect. Here are profiles of frightened, sick people and their families. If one goes no further than that, what is a reader to think other than that the reporter is convinced those ailing are, in fact, victims of bad policy?

The story has next to nothing on such important questions as whether the anxiety is backed by any suggestion of more illness than usual, or the ease with which a segment of the public can see a link where none exists.


Four days later, and somewhat ironically, the Chronicle published an article, by medical reporter Sabin Russell, with the headline, “Health experts can’t link spraying to illness.” Unlike Kay’s earlier work, Russell’s piece was careful to address some of the specifics that Petit had called for at the Tracker. Unlike Kay’s earlier, front-page story, however, it was buried far inside the paper, on page B-4. According to the article:

Three-quarters of the citizen reports failed to pinpoint the time or place of possible exposure to the spray, according to the state analysis, and “very few” provided addresses to help researchers match exposure to location.

The state study also noted that, although there were 75 reports of patients seeking medical care after the spraying, most of the reports - even those requiring medical attention - were consistent with rates of common respiratory problems.

Apart from Russell’s article, however, the Chronicle seemed hell-bent on proving that pheromone spraying was unnecessary. In March, about a month before her story about the health complaints from spraying, Kay wrote another story that presented the cases of four scientists opposed to the spraying - two renowned UC Davis entomologists, a UC Berkeley agro-ecologist, and a UC Santa Cruz botanist. Kay did not offer a response from the government scientists, except to say: “In the face of criticism, U.S. Department of Agriculture and California Department of Food and Agricultural scientists stand firm that there must be quick aerial spraying to eliminate the moth.”

The question that Kay never addressed, but should have, was why the USDA scientists stood firm behind the pheromone spraying. Combined, they have hundreds of years of experience in invasive moth research; as agriculture department spokesman Steve Lyle said, “It’s not an even playing field on the science. There are just a few people in the world who are experts on this.” In the bowels of her article about the scientific opposition to spraying, Kay inconspicuously disclosed: “The pheromones aren’t toxic to moths, animals or people, they say, but curtail moth populations by disrupting mating.” It may have been scientifically possible to refute that statement, but Chronicle never even seemed to try. Two months later, in another editorial, it was still blindly equating pheromones to more traditional pesticides:


It can’t get more obvious than this: Rooftop crop-dusting across the Bay Area unnerves people and demands serious explaining.


Such misleading statements, combined with a general apathy about digging up whatever government scientific information is available, are not helpful to readers. The Chronicle’s coverage reflected a belief that scientists working for the government, even ones with long and seemingly credible histories, aren’t worth talking to. The paper had an opportunity to introduce a voice of moderation into the hysteria surrounding the spraying. Instead, it rode with the public’s fear.

There is a reasonable scientific debate here, especially about the effectiveness of pheromone treatments, and the length of time the moth has been in California. It was quite reasonable to demand further testing on the safety of this particular formulation of Checkmate, and a dumb error by the state not to have done so before it started spraying. Following the public backlash, California agreed to produce a detailed environmental impact report by the fall. One imagines, however, that the same outcome might have been reached without hyping a bunch of ambiguous illnesses —journalistically, there are more responsible ways to hold the state accountable.

The USDA scientific working group’s original recommendation was, in fact, to pursue pheromone treatment while developing other, better methods. And after all the hyperbole, that’s how the story ultimately seems to have ended. Two weeks ago, the state decided it had found a better method, one that utilized the latest in sterile-moth-release-technology. With no new or better information about the toxicity of the pheromone, the governor called off spraying in urban areas, leaving the drama-ridden public debate over the safety of the pheromone largely unanswered. And now, probably, irrelevant.

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Eric Simons is the author of The Secret Lives of Sports Fans: The Science of Sports Obsession (Overlook Press, 2013), and the editorial director at Bay Nature magazine.