The Los Angeles River in Long Beach, CA
Credit: Getty Images

The polyphagous shot hole borer, a brown-black beetle from southeast Asia, never gets bigger than a tenth of an inch. It breeds inside trees; pregnant females drill into trunks to create networks of tunnels where they lay their eggs. The beetles also carry a fungus called Fusarium; it infects the tunnels, and when the eggs hatch, the borer larvae eat the fungus.

Unfortunately Fusarium also disrupts the trees’ ability to transport nutrients and water. Holes where the beetle bored into the tree get infected and form oily lesions. Sometimes sugars from the tree’s sap accumulate in a ring around the hole—that’s called a “sugar volcano.” The tree dies, and the wee baby beetles fly off to continue the circle of disgusting life.

This would just be a scary story for arborists and tree-huggers, except: Fusarium dieback is on track to kill 26.8 million trees across Southern California in the next few years, almost 40 percent of the trees […]