A roaring fire after a productive day of autumn gardening tasks, hiking up to First Water, or, heck, reading email at Bean Town, is a seasonal balm. In moderation, piling logs and lighting twisted cones of newspaper kindling can impart a sense of "I'm in charge here!" And it's a sense that's duplicated by very few old-school activities. Dialing a rotary phone. Drinking bathtub gin... You get the idea.

As it turns out, even without all the carbon monoxide and particulate matter, it's not the just combustion of fuel that's the worry. Rather, it's a new danger presented by a highly-invasive pest that may be hitching a ride to town on your next shipment of oak firewood. 

Never heard of Agrilus coxalis, Golden-spotted oak borer?  Well, a small army of entomologists and arboriculture professionals are doing their darnedest to fill the information gap, including Sierra Madre Tree Advisory Commission member Caroline Brown. At last week's City Council meeting, Brown called out the threat of this unchecked arthropod that is now decimating oak species at a woodland near you. 

And it's getting closer, perhaps hiding in the next friendly firewood truck that rolls up the 5 from San Diego County.

As a steward of city trees, Brown is doing her part to protect the oak species of the foothills and public streets. Any uninvited pest could have rippling of consequences for property values, city abatement costs, wildlife habitats, air quality and, in the end, perhaps the very character of Sierra Madre. Which is not to mention that beautiful oak growing in your yard.

Sure, the Golden-spotted oak borer has had a long history in Arizona, Mexico and Guatemala since the late 1800s. But GSOB wasn't known to be inside Southern California until early in this century when it was noted by the California Department of Food and Agriculture during a periodic survey.   

Meanwhile, three species of oak, Q. agrifolia, coast live oak, Q. kelloggii, California black oak and Q. chrysolepis, canyon live oak, were rapidly declining in southeastern San Diego beginning in 2001. At the time, it looked like drought stress.

But in 2008, U.S. Forest Service entomologist Tom Coleman discovered active larvae aggressively feeding on the soft wood layers inside the bark of Cleveland National Forest oaks.

The metallic green-winged adult with its flat head and six orange spots on black wings was a brand new invader, without known predators in Southern California.  In 2008, 17,000 oak trees were weakened and dying in San Diego County. And in 2009, the total had grown to 28,000 decimated. Officials believe the likely transport for the insect was firewood carried in from Arizona or Mexico. Subsequently, public wood permits have been suspended indefinitely in the Cleveland National Forest. 

"As of today, the infestation continues to expand," says Mark Hoddle, director of the UC Riverside Center for Invasive Species. "Thirty-to-40,000 San Diego county oak trees are dead or in advanced states approaching death."  Hoddle developed the San Diego woodborer study with Coleman. GSOB has not been seen in Los Angeles county.

UCR scientists have targeted a short list of natural predators.  "We've found some in Arizona. We're testing natural parasitoids in the quarantined area, and assessing their safety in California," says Hoddle. 

Locating a biological predator and developing sufficient numbers to combat the GSOB, which has increased exponentially, is a challenge. It may take three to five years to safely develop controls for the beetle invader.   

The life cycle of the Golden-spotted oak borer is about a year. Eggs are laid in early summer in the bark of healthy, mature oak, often with a 12" or larger trunk diameter.  "The larger the tree, the greater the food source," says Hoddle. The slender adult is about 1 cm long, or one half of an inch.  Ten of them can fit on the head of a penny.  If you're not looking for them, they're easy to miss. 

Their eggs hatch into hungry white larvae with two prongs at the tip of their abdomen. This legless form can reach nearly two inches in length and feeds under the bark in random black patterns, or galleries. Before developing into the pupal stage it folds in half, sort of crinkled, like an accordian.

Feeding galleries may be exposed by woodpeckers chipping away at bark in search of larvae to eat. Dark or red, wet staining on the exterior of the gray bark might indicate a feeding gallery below. The larvae eat the tree's soft cambium and phloem, stripping this growth and energy circulating system. The tree then starves, having its food supply cut off.  Twig dieback and canopy thinning may be early indications after a two-year GSOB infestation.  

In December the larvae hibernate, and begin warming up again as pupae in spring.  The flying adults emerge through an exit hole they make in the bark, and lay eggs in the bark of healthy or infested oaks.

As oaks die, entrepreneurial individuals and wood providers continue to clear trees for sale, often not realizing they are infested. Los Angeles County residents are urged not to purchase or transport any oak wood for pallets or fuel which may have come from San Diego county's Cleveland National Forest or may have been blended with wood from Cleveland National Forest.

Other recommendations to help prevent the spread of the Golden-spotted oak borer to L.A. County and farther north:

• Do not transport firewood in or out of campgrounds or parks.
• Leave unused firewood at each campground.  Collect and use new firewood at the next site.
• Chip any suspect oak wood into one-inch-or-smaller pieces. 
• Do not purchase mulch containing oak unless the source can be positively identified as outside of the "dirty" or infested area.
• Use three-quarter-inch-minus mulch, which has been chipped and screened to a size that has likely cut and killed hibernating larvae.
• Cover stored oak firewood with thick, clear plastic, securing all edges to prevent beetles from escaping.
• Season oak firewood.  Remove the bark and destroy it, and place wood in direct sunlight to kill colonies.  Rotate in sun every few weeks. 

If you're not sure where that guy got the wood on the back of his pickup, don't buy it. Even if he's practically giving it away. What looks like a fantastic bargain in lean economic times could be the beginning of the end of the canopy of old growth coast live oaks that cool the canyons, shade city streets, provide habitat and food for wildlife, improves air quality and contributes to the serenity and beauty of Sierra Madre. 

For more information or to report a possible infestation of GSOB, call our local County Agriculture Commissioner's office, located at 12300 Lower Azusa Rd. in Arcadia.  Their phone number is 626-575-5484. You can also report infestations and get more information at the statewide Integrated Pest Management Program website.

An earlier version of this story incorrectly reported that Caroline Brown spoke on the Golden-spotted oak borer at a Tree Commission meeting. We regret the error.