Be on the lookout for emerald ash borers:
• Adult beetles are elongated and slender, with bright, metallic-green wing covers and purplish-red abdomens.
• Larvae have reddish brown heads and cream-colored bodies. They have 10 body segments, with brown pincerlike appendages on the rear.
• Larvae create "S"-shaped markings beneath the bark of trees as they grow and eat.
• Infected ash trees first will display dead branches, followed quickly by decay throughout.
There's a big, green tree-killing mob heading toward Chattanooga, and City Forester Gene Hyde is trying to brace for it.
Hyde's trying to keep tabs on the spread of the emerald ash borer, a green Asian beetle that's decimating ash tree populations across the country.
"There are 8 billion -- that's billion with a 'b' -- ash trees in North America. Every one of them is at risk," Hyde said Wednesday before checking a beetle trap at North River Soccer Complex in Hixson.
That includes the estimated 250,000 ash trees inside the city limits, about 2,000 of which are on city rights of way, Hyde said.
The invasive beetles first were sighted on American soil in 2002 in Detroit, Mich., according to the U.S. Department of Agriculture. Scientist suspect they arrived on untreated wood used in cargo packaging from Asia. Without any natural predator, the bugs have been spreading ever since, leaving tens of millions of dead ash trees in their wake.
The adult beetles only eat ash leaves. But their larvae bore into trees and feed on phloem, a critical part of the tree's vascular system, Hyde said. Once individual trees are heavily infested, they can't transfer water or food efficiently and they begin to die.
Hyde said the bad bugs have been spotted as close as Monroe and Smith counties, which are each about 100 miles from Chattanooga.
He hasn't found any in Chattanooga yet, but to prepare for the inevitable Hyde placed sticky, pheromone-coated traps at 16 locations throughout the city. At the first sign of one of the little green devils in the traps, Hyde will be able to act. That will mean first treating the city's "high value" trees -- those that are on rights of way and could harm people or property if they fall.
Treating means either injecting pesticide into the trees, spraying the bark or pouring chemicals into the root systems. After the critical trees are treated, Hyde will have to assess costs and take the next step, he said.
The bugs live in their beetle form for about three weeks, according to the agriculture department, so they don't travel long distances. The insects are most likely spread by people transporting ash wood that is infested with larvae or eggs, Hyde said.
Because of that, the federal government has placed quarantines in 10 states where the beetles have been found.
Aside from the safety threat of dead trees dotting the city, Hyde said ash trees make up about 1 percent of Tennessee's overall tree canopy. Those account for millions of wildlife habitats throughout the state.
Hyde is asking residents who have ash trees on their properties to keep a look out for the invasive bug.
"Anyone who has ash trees should work out a plan to have their trees treated," Hyde said.
The city will treat trees on public land, but private property owners will need to seek professional help with the pests.
Contact staff writer Louie Brogdon at email@example.com or 423-757-6481. Follow him on Twitter at @glbrogdoniv.