SAN DIEGO -- Residents were being asked Monday to be on the lookout and report any sightings of a beetle that is contributing to the death of thousands of oak trees in San Diego's East County.

Infestations of the gold-spotted oak borer have been identified in Julian, Alpine, Pine Valley, Descanso and Morena Village, according to San Diego County officials.

The pest has been in the county for several years, but only recently did officials discover that the insect, combined with ongoing drought conditions, is killing oak trees.

The beetle -- which is brown with gold spots on its wings -- attacks healthy, mature oak trees on main stems and large branches. Its larvae feed on the underside of the bark, causing strips or patches of the tree to die.

The damage is seen in several types of oaks, including the coast live oak, canyon live oak and California black oak.

Experts think the gold-spotted oak borer may have spread to San Diego County under the bark of firewood. County officials urged the public not to transport firewood in or out of the county until more is known about the pest.