The trees that make Southern California shady and green are dying. Fast.

A crew from the West Coast Arborists cut down another tree on the grounds of Craig Regional Park in Fullerton that is infested with the polyphagous shot hole borer beetle.

A pedestrian walks past the mounds of dirt where trees once stood in Craig Regional Park in Fullerton April 7, 2017. The dying trees are infested with the invasive beetle, the polyphagous shot hole borer and are literally being eaten and weakened one tunnel at a time.

Looking at a cross section of a tree that was destroyed by the polyphagous shot hole borer beetle that was eaten and weakened one tunnel at a time.

Ranulfo Peralta with West Coast Arborists cuts-down another infested tree in Craig Regional Park in Fullerton.

The larvae of a pacific flat headed borer wiggles and moves around in the caverns of an infested tree in Craig Regional Park in Fullerton.

Dr. John Kabashima with the University Of California Agriculture and Natural Resources inspects an infested tree on the grounds of Craig Regional Park in Fullerton.

Dr. Akif Eakalen, plant pathologist at UC Riverside inspects the cross-section of a tree in Craig Regional Park in Fullerton.

Dr. Akif Eakalen, plant pathologist at UC Riverside, Dr. John Kabashima and research assistant....look at an infested tree in Craig Regional Park prior to the tree being cut down.