As if being on guard for the glassy-winged sharpshooter and the light brown apple moth weren’t enough, Napa’s wine industry is now on the lookout for the western grapeleaf skeletonizer.

A state lab has confirmed that an adult male skeletonizer moth was found in a trap on Mount Veeder Road on Aug. 8, said Dave Whitmer, Napa County’s agricultural commissioner.

Meanwhile, three months after a first light brown apple moth was found in a Napa residential neighborhood, a second light brown apple moth was found Aug. 21 in a trap at Highway 29 and South Kelly Road, prompting a quarantine on plant material leaving the area and the placement of more traps to gauge the extent of the infestation.

“We will now place 25 traps per square mile in the nine square miles surround the find,” Whitmer said Wednesday in a prepared statement. “We just can’t take any chances that the moth will become established in Napa County or that we inadvertently allow it to spread elsewhere.”

County inspectors will check nearby vineyards before wine grapes are allowed to be picked, Whitmer said in an interview. Additional traps will be set near the regional compost facility near the airport and the south county flea market, he said.

Like the May find of a light brown apple moth near Solano Avenue and West F Street in west Napa, last week’s discovery near American Canyon involved a single moth, Whitmer said. Additional traps will tell inspectors if there is a larger problem.

The light brown apple moth is considered a major threat to the wine industry and also devours more than 200 other types of vegetation, including many domestic plants. The federal government is paying for the statewide eradication effort.

In west Napa, the state is hanging pheromone strips that make it hard for male moths to find females. This program will continue into the fall.

The western grapeleaf skeletonizer is already well established in many grape-growing parts of California. The pest consumes grape leaves and fruit and causes secondary fungal damage, Whitmer said.

“If we can keep it from establishing here, it would be one less thing that our wine industry would have to treat,” Whitmer said.

The agricultural commissioner’s office is putting out additional traps baited with the female skeletonizer moth’s pheromone to learn if the find on Mount Veeder is an isolated one or part of a bigger problem, he said.

Besides feeding on grape leaves, the bug also can be found on Boston ivy and Virginia creeper. When it consumes a grape leaf, it leaves behind a distinctive lacy “skeleton,” Whitmer said.

Whitmer would like members of the public to keep their eyes open. During the larval stage, the bug has bands of color around its body.

For more information and photos of the skeletonizer, visit the Napa County Agricultural Department’s Web site at www.co.napa.ca.us.

The county was able to find the light brown apple moths and now the western grapeleaf skeletonizer because it maintains hundreds of traps that serve as an early-warning system for insects that could threaten local agriculture and backyard gardens.

A half-dozen county employees are constantly checking the traps for a long list of feared intruders including the Mediterranean fruit fly, the Japanese beetle, gypsy moths and vine mealy bugs, Whitmer said.

At the top of Napa’s most-wanted list are the glassy-winged sharpshooter, which can carry Pierce’s disease, and the light brown apple moth.

The county has been on the lookout for the sharpshooter since 1999, when the first bug was found here. Others have been discovered in nursery stock, but there have been no infestations, Whitmer said.

The federal government should be doing more to keep invasive species out of the U.S. so eradication battles don’t have to be fought on these shores, Whitmer said. “At the local level, we’re having to deal with too much after they get in,” he said.

A new agricultural bill pending in Congress may provide funds to block pests and diseases at the border, he said.

Anyone who thinks they have found evidence of a skeletonizer should call Whitmer’s office at 253-4357.