//metrognome logo// The New York City Parks Department planted 15,000 trees last year. So it was big news last week when the same people who make the city greener every day were summoned to Central Park to do the opposite. Yes, folks, the dreaded Asian Longhorned Beetle -- that arboreal al Qaeda -- has struck again. This time, it cost Central Park just one sugar maple and one Norway Maple, but by breeching the innermost walls of the city's Emerald Empire, these pernicious pests have undermined the confidence of every tree-hugging New Yorker. Like the World Trade Center before it, an internationally known New York shrine is under attack. Half of the park's 26,000 trees -- including all 1,800 of the American elms that line the famed Literary Walk -- are at risk. "The enemy has established a beachhead and it must be repelled," said new Parks Commissioner Adrian Benepe, demonstrating his predecessor's gift for soundbites (but not for wardrobe; Benepe showed up in a suit and tie to toss infested tree branches into a wood-chipper. A suit and tie! On a Parks Commissioner! Couldn't somebody have dug out Henry Stern's old lumberjack costume?) Delving further into World War II imagery, Benepe held up two dead beetles -- they look like roaches in tuxedos -- and implored New Yorkers to organize "civilian defense"-style patrols to spot the beetles when they emerge in June, leaving circular exit wounds that make trees look like the victims of mob rubouts. Benepe's violent rhetoric was barely hyperbole. It doesn't take a hotshot epidemiologist to see that the city is under attack and the destruction is spreading. From their first sighting in Greenpoint in 1996, these Asian beetles have eaten a swath of destruction from Bayside (Feb. 1999) to Flushing (July, 1999) to the Upper East Side (Aug., 1999) to the Lower East Side (June, 2000) and to Midtown (Oct, 2001, when most people's attention was temporarily diverted). Roughly 3,500 infested trees have been chopped down, ground up and burned -- sacrificed in hopes of forestalling the beetles' advance. Yet the beetles keep coming, an insidious, systematic, relentless invasion. "It's actually a lot like terrorism, because there's an element of surprise," said Fiona Watt, chief of forestry for the Parks Department. "And, as usual, New York City is taking the hit for the rest of the country." One skeptical reporter -- OK, it was me -- asked Watt why the city failed to protect its crown jewel after the beetles showed up in an Upper East Side playground three years ago. "This is a dastardly foe," Watt said. The state and federal government has spent millions to inspect 120,000 trees and will inject 80,000 with a new pesticide that kills adult beetles this year. Sounds good, right? Think again: There are 5.2 million trees in New York City. Compared to this, Sisyphus was pushing a cotton ball up that hill. --30-- gersh.kuntzman@verizon.net