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From the February 2001 Conservationist

Asian Longhorned Beetle

By Peter Frank

In New York City, neighborhood trees were being ravaged, their trunks riddled with holes. Determined to catch the culprits in the act, a Brooklyn resident set up watch. Patiently, he waited, scrutinizing each passerby for displays of vandalism. No human criminals appeared, but a large back-and-white beetle crawled out from one of the holes in a tree trunk.

Surprised, the resident promptly called the New York city Department of Parks and Recreation. A New York City forester visited the site but couldn't identify the strange beetle. Instead, he sent it to Cornell University, where it was positively identified as the Asian Long-horned beetle (Anoplophora glabripennis).

By now you have probably heard about this newest threat to New York's trees. Native to china, Japan and Korea, this adaptable insect survives over a range of climatic zones that roughly corresponds to the eastern United States from southern Mexico to Nova Scotia. Just as many of our immigrant ancestors had done, this new visitor made its first stateside home in New York City. Populations have since been discovered in Chicago and on Long Island.

The Asian Long-horned beetle is an interesting-looking creature, with striking white bands on antennae that are twice as long as its body. Adult beetles are 3/4" to 1-1/4" long. Their elongated black feet have a whitish-blue upper surface. The Chinese call it the starry sky beetle, referring to the arrangement of white spots on a glossy black body.

Doing Its Dirty Work

The concentration of egg-laying sites and activity of larvae, which tunnel into the heartwood after hatching to feed, along with the exit holes made by emerging adults are very destructive to trees. Before the tree dies, however, the continued boring often weakens it to the point where limbs and branches break and fall during wind and rainstorms.

In the United States, the beetles prefer maple species including Norway maple, silver maple, sugar maple, red maples and box elder. Other known hosts include horse chestnut, black locust, elm, birch, willow, poplar and green ash.

The insect's life cycle begins when a female beetle chews a small depression, called an oviposition site, in the smooth bark of a host tree. There, she deposits a single fertilized egg. Each female lays 25 to 30 of these eggs that hatch into larvae within two weeks.

Larvae bore into the tree, through in inner bark and into the heartwood. The larvae's tunnels, called galleries, disrupt water and nutrient flow between the roots and the leaves, eventually killing the tree. Larvae mature, pupate and emerge as adult beetles that chew their way back out of the tree. The exit holes, which are 3/8" or larger, can be found all over an infested tree trunk, on branches larger than 1 ½" in diameter and on exposed surface roots.

Exit holes and oviposition sites are two of the clues that entomologists use to locate infested trees. Other signs include sawdust, called frass, that is pushed out of the tree by tunneling beetles. The accumulated frass is often found on branches and at the base of infested trees.

Hitchhiking to America

It's unclear how the Asian Long-horned beetle arrived on our shores. Most likely, the beetle stowed away in untreated wood shipping materials bound from China and arrived at the Port of New York in the early 1990s.

Since the infestation, new laws have been passed requiring that wood crates, pallets and shipping material from China be kiln dried or treated to kill wood-borne pests. Federal inspectors who examine incoming shipments are working to prevent the beetle from entering other U.S. ports.

Foresters Fight Back

The battle against this formidable foe has just begun. The Asian beetle has no known natural predators in this country and appears to be pesticide-resistant. Lacking these weapons, entomologists are turning to quarantines and eradication programs to halt the beetle's advance. Inspectors are systematically examining trees in new York city and on Long Island. The only available method to eradicated beetles found in infested areas to restrict the movement of wood debris and plant material that might harbor the beetle. Prior to the quarantine, and unsuspecting arborist may have transported the beetle to Amityville, Long Island (where it is now being found with some frequency) on infested landscape debris. From there the adults beetles may have emerged and migrated from the wood pile into nearby neighborhood trees.

Restoration Begins

A partnership of federal, state and city agencies and volunteers is working together to restore the urban forest being lost to this destructive pest. Working hand-in-hand with citizen volunteers, DEC's New York Releaf program has developed tool kits and training sessions to raise public awareness about the beetle. Trees New York, a not-for-profit urban forestry organization in new York City, has organized community plantings to help restore trees lost on private property such as cemeteries and back yards. Since the inception of the restoration effort, 4,000 trees have been planted.

On Long Island, towns and villages have also joined the partnership to restore the lost tree canopy. New plantings consist only of species resistant to beetle damage. The list of acceptable "non-host" trees includes honey locust, dawn redwood, oaks, lindens, sweet gum, and tulip tree.

The best defense against the Asian Long-horned beetle is early detection and fast action. Concerned citizens have reports many of the infected trees and beetle sightings in New York. You can help. Whether you are out for a walk or sitting on a park bench, take a moment to see if you can spot this destructive pest.

Learn to recognize the Asian Long-horned beetle and the damage it causes. The trees you save may be your own.

Peter Frank is coordinator of DEC's urban community forstery program.

Photo: USDA Forest Service