Asian beetle poses threat to urban trees

A new pest, the Asian longhorned beetle, has arrived in the United States, threatening hardwood trees in New York, Chicago and other cities. Entire neighborhoods of trees have been cut down to stop its spread, according to the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS).

The beetle is entering the country via solid wood packing materials, such as pallets and crates, that came from China. If it becomes established in the United States, officials say, it could turn into the gypsy moth of the 21st century, destroying millions of acres of hardwoods.

According to APHIS, the beetles attack trees including horse chestnut, poplar, willow, elm, mulberry, black locust, and Norway, sugar, silver and red maple. The insects bore into the trunks of the trees and lay their eggs inside, then spend all but the summer months hiding inside the trees.

No one has developed a trap for the beetle, and insecticides are ineffective because they typically do not penetrate into the beetle’s hiding places. Removing and destroying infested trees is the only way to eradicate the beetle. So far, the pest has been found in California, Illinois, Indiana, Michigan, Wisconsin, New York, New Jersey, Florida and the Carolinas.

Portions of New York City and Nassau and Suffolk counties; Chicago; DuPage County, Ill.; and Summit, Ill., have been designated as quarantined areas, according to APHIS. The quarantine means that infested tree trunks, limbs and debris cannot be moved to noninfested areas.

In the Ravenswood neighborhood on Chicago’s North Side, inspectors identified 473 infested trees, most of which were in an 11-block area, says Joe McCarthy, a forester with the Streets and Sanitation Department’s Bureau of Forestry. Officials believe the infestation occurred as long as seven years ago when a neighborhood hardware manufacturer imported raw materials in wooden crates from China.

Of the trees thus far removed in Chicago, 323 were street trees; the rest were in yards. Elm, silver maple, green ash and horse chestnut were the most commonly infested species, according to McCarthy. The telltale signs of infestation were holes about a half-inch in diameter that emitted sap late in the summer.

“We don’t know whether we’ve got it under control; this is going to be a multiple-year program,” McCarthy says. “Entire blocks are going to be practically denuded of trees.” In fact, of the 450,000 street trees in Chicago, 70 percent are potential hosts to the beetle. To encourage residents to report cases of infestation, the city agreed to pay for cutting down and removing the trees. It also will plant replacements.

As New York City and Amityville, N.Y., have demonstrated, stopping the Asian longhorned beetle is costly. Suppressing a 1996 infestation in the two cities cost the state and federal governments more than $4 million, according to USDA.

Asian longhorned beetles are about an inch long, shiny and black with bright white spots. Each adult has a pair of curved, black-and-white antennae that are longer than the body. In the absence of a trap, APHIS and cooperating state inspectors survey areas for the presence of the beetle by carefully examining hardwood trees for exit and entry holes. The beetles spread quickly when they get into an area with sufficient hardwood trees. They typically attack a single tree at first, exhaust it as a food source and spread to nearby trees.

Officials note that infestation can best be prevented by stopping the beetle’s entry into the country. To accomplish that, APHIS officers have stepped up their visual inspections on high-risk cargo in areas such as distribution warehouses.

They also have issued pest alerts to port-of-entry personnel, contacted U.S. importers and targeted high-risk importers and Chinese exporters for outreach and increased inspections. The officers refer infested shipments for fumigation, impose quarantines and conduct intensified visual inspections around confirmed sites in conjunction with state officials.

For more information on the Asian longhorned beetle, contact APHIS, (301) 734-8295; or access the web site (http://www.aphis.usda.gov).