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INSECT TRAPS have been installed across the county to prevent the spread of the light brown apple moth. JOHN GREEN Staff
HALF MOON BAY — San Mateo County officials are taking action against the light brown apple moth amid growing local controversy over the pheromones used to disrupt the destructive insect's mating cycle.

Starting Monday officials with the California Department of Food and Agricultures will hang a series of red "twist ties" coated with the

pheromone in trees along parts of Pescadero and Half Moon Bay where the moth has been found — 250 twist ties per acre in a 650-foot radius around each infested site.

Then, in August, the department plans to start aerial spraying of several Bay Area parks and cities where the incidence of the light brown apple moth is too high to make the twist-tie solution effective. Those locations include Daly City,

South San Francisco, Colma, Brisbane, San Bruno, and the northern tip of Pacifica.

The light brown apple moth, inadvertently imported from New Zealand, first appeared in Alameda County in March 2007 and has spread to 252 square miles across the Bay Area. It feeds on more than 250 varieties of plants in its larval stage and is deemed a major threat to the state's agriculture industry.

Although the Peninsula has only been lightly affected by the infestation so far, county Agricultural Commissioner Gail Raabe says now is the time to make sure it stays that way.

"If other countries see that we are not working to get rid of this, the whole county, the whole state, would be under a quarantine from here on out.


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Raabe supports both the twist-tie method, a low-impact way to discourage the mating patterns of the moths without killing them, and the aerial spraying. The San Mateo County Department of Agriculture has been trapping the moths since last April, with five traps per square mile countywide. It also imposed a quarantine on 38 production nurseries, 29 cut-flower and vegetable growers and 22 retail nurseries after finding the moth pupae at several locations. The quarantine involves inspections every two weeks, according to Raabe.

Concerns over the potential health risks of spraying urban areas with a new kind of pheromone has drawn such intense opposition among residents of San Francisco, Marin and Alameda counties in recent weeks that on Monday, state Sen. Carole Migden called for a moratorium on any aerial spraying until the pheromone product, which is currently being reformulated, can be proved safe for human exposure.

State officials received more than 600 reports of adverse health effects following two aerial spraying sessions that occurred late last year in Santa Cruz and Monterey counties, where the light brown apple moth was endemic. Residents reported symptoms that included breathing problems, eye irritation, coughing and headaches.

Officials have maintained that the product used in those sprayings, called Checkmate LBAM-F, is safe and that the symptoms could have been caused by an illness or seasonal allergy.

A statement prepared after the fact by the state Department of Pesticide Regulation and the Office of Environmental Health Hazard Assessment says the symptoms reported by residents "could be consistent with inhalation of a sufficient amount of applied material," but the pheromone product was applied at a low enough level to raise concerns.

The statement also says that "not all health effects can be predicted" in children, the elderly and the chronically ill, and calls for a formal study tracking the short- and long-term health impacts of the product.

Much of the concern around the Checkmate product does not focus on the pheromone itself — pheromones are a well-established method for fighting moth infestations — but on the inert ingredients that form the "capsule" around the chemical that allows it to take the form of a spray that falls to earth. The product manufacturer refused to disclose the inert ingredients until a judge ordered the CDFA to do so last October.

CDFA Primary State Entomologist Kevin Hoffman said his agency has no alternative to using the aerial spraying method, which he characterized as "completely acceptable." The alternative, he said, would be a forest of twist ties that would take a "small army" to distribute. 

The light brown apple moth was deemed such a threat to California last year that the U.S. Department of Agriculture obtained an emergency exemption from the federal Environmental Protection Agency to begin using Checkmate LBAM-F right away, rather than subject it to analysis and registration by the state Department of Pesticide Regulation, according to state department spokesperson Veda Federighi.

Federighi said such exemptions are common for pesticides used to combat moth infestations, but are not commonly issued directly to the USDA from another federal agency.

The U.S. EPA's database of federally registered pesticides does not contain Checkmate LBAM-F.

Scientists in New Zealand currently are testing several new formulations of the pesticide; one as a waxy flake that would stick to trees. The goal is to find a product that will last longer and not require re-application after 30 days, said Hoffman. It is not clear whether the USDA intends to seek an exemption for that product as well.

The controversy has been muted in San Mateo County. Six people showed up to an information session on the twist ties in Pescadero on Tuesday night, and only two locals came to another session in Half Moon Bay.

"I have concerns about the health risks. My first question when I came was, is this all necessary? Now I'm beginning to understand the issues there," said Half Moon Bay resident Beth Craig, whose family farm has several pregnant animals that live outdoors. "I still don't want my property to be sprayed." Danny Santos disagreed. As a pest control expert with Nurserymen's Exchange, a major Coastside flower and plant grower, Santos regularly applies an organic pesticide to get rid of all moths and damaging insects in one fell swoop and said a targeted method could be even more beneficial.

"I think the species is here to stay, like so many," said Santos. "There's too many plant hosts. If we do nothing, then we have a problem."

Staff writer Julia Scott can be reached at 650-348-4340 or at julia.

scott@bayareanewsgroup.com.