The drought, now in its fourth year, is creating severe and dangerous threats to the Hill’s native trees — pines and oaks. But other dangers also are threatening the local forest.

Residents are familiar with the damage bark beetles bring, especially during droughts. The bark beetle is actually a native pest, but during droughts when trees have insufficient water to generate pitch, the beetles’ attacks create more devastation. And the Goldspotted oak borer is now present and attacking many black oaks. The GSOB is an invasive pest that first arrived in California about 10 years ago in San Diego County.

Now, local Forester John Huddleston is warning residents about another native pest — the Black Pineleaf scale.

In 1998, the U.S. Forest Service wrote, “The Black Pineleaf scale (Nuculaspis californica) belongs to a group of sucking insects called armored scales. Concealed under their protective shells, these scales insert their mouthparts into their hosts, removing sap and, possibly, injecting toxic enzymes secreted in the saliva. … Infestations are generally localized, sometimes in just a few trees … Occasionally, however, epidemics cover several thousand acres of forest … Large areas of Jeffrey and Ponderosa pines in northeastern and Southern California, for example, have had recurring infestations since 1940.”

In its 2013 report, the California Forest Pest Council wrote, “High population densities of Black Pineleaf scale have impacted approximately 200 acres of Jeffrey pine in Idyllwild.”

Huddleston believes the Pineleaf scale is “… a bigger threat to the populated area of Idyllwild. More than 5 square miles of pines are heavily infested. I believe it to be in about 95 percent of the trees.” Consequently, he has contacted Serguei V. Triapitsyn, Ph.D., principal museum scientist and quarantine supervisor, Department of Entomology, University of California, Riverside.

Last month, he and Triapitsyn took a few samples from the middle of Idyllwild.  “We found scale on every tree we sampled, including Jeffrey pines, Ponderosa and Coulter,” Huddleston reported.

However, Triapitsyn was uncomfortable “mak[ing] comparisons with other recent insect infestations in Southern California.” He emphasized that the Black Pineleaf scale is a native species and GSOB is an invasive species.

One cause of the spreading scale appears to be the inability of a native wasp that preys on the scale to keep up with its expansion. Local Arborist Deborah Geisinger suggested that either air pollution or greater use of pesticides, such as carbaryl and malathion, might be affecting the wasp population, which limits its ability to control the Pineleaf scale.

Local Riverside County Fire Department Forester Gregg Bratcher and Kevin Turner, GSOB coordinator for University of California Agricultural and Natural Resources in Riverside, acknowledged the Black Pineleaf scale’s presence on the Hill.  Both stressed that the scale is always present among local pines; however, they believe the current drought is also abetting its danger. Lack of water inhibits pitch production and permits bark beetles to inflict more damage and death on the pines in a similar manner as lack of water affects the trees’ ability to fend of the scale or the natural wasp predator to keep pace with the Black Pineleaf scale expansion.