Cal Fire officials recently spotted a California black oak tree in Idyllwild, CA, that was infested with the gold spotted oak borer. This beetle has already destroyed 80,000 oak trees in San Diego County, but officials hadn’t expected to see it so far outside of the estimated zone of infestation. “Our concern is that it’s been found 40 miles outside the zone of infestation. That’s a long way. How did it get here?” asks Julie Hutchinson, Battalion Chief and Cal fire spokeswoman. Hutchinson thinks it was carried into the Idyllwild area in a load of firewood and cautions people to use firewood where they’ve bought it.
The adult gold spotted oak borer is about a half-inch long and forest green, with six golden spots on its wings. The larvae feed on the soft tissues of oak trees directly under the bark. This soft tissue is the supply route for water and nutrients, and the damage caused by the beetle stresses the tree until the tree dies.
The infected tree was discovered when a Cal Fire employee noticed that the tree had much smaller leaves and the leaves were starting to turn brown. When the tree was checked a few weeks later, the tree was dying and the leaves were brown. About a dozen larvae were extracted from the tree and DNA-analyzed to confirm the species. The tree was subsequently taken down and shipped to San Diego County, within the area the beetle has already infected. The extent of the infestation in Idyllwild won’t be determined until spring, when adults emerge.
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