Air Date: Week of October 11, 1996
Maple leaves create some of the most spectacular autumn foliage. But some maples are being threatened by the Asian long-horned beetle. New York's Park Commissioner Henry Stern fields questions from Steve Curwood on this newly arrived killer pest.
CURWOOD: Trees in the northeast face another threat besides clear-cuts. The Asian long-horned beetle, a small black bug with white spots, hitched a ride to the US probably from China or Japan, probably in a stack of lumber. It has turned up in Greenpoint, Brooklyn, where it is boring into its favorite food, maple trees, and killing the tree in the process. Henry Stern is New York's Parks Commissioner and he's been monitoring the outbreak. I asked him what an Asian long-horned beetle does to a maple tree.
STERN: Oh, it's terrible.
STERN: What it does is they chew into trees with their mandibles, that's their sort of jaws. Then they lay eggs, which develop into larvae. The larvae feed on the heartwood inside the tree. And once the larvae have developed, like the chickens in an egg, once they develop, they bore their way out, leaving large exit holes that can leave the host tree susceptible to secondary pathogens.
CURWOOD: So what kind of damage have you seen these beetles cause so far among these 200 trees?
STERN: Well, enough of them can kill a tree, and so far they've affected 150 to 200 trees. Mostly maples and horse chestnuts. They seem to be the trees of choice for these predators.
CURWOOD: That's funny, because maple's a pretty hard wood, you know, if you try to saw it or work with it it's pretty tough. But it's tasty to these guys, I guess, huh?
STERN: Sweet maple.
CURWOOD: [Laughs] You know, there must be, what? Twenty-five, 30 percent of the large trees in the Adirondacks and in the northern forest here in Massachusetts and Vermont are maples, and this time of year we just love the way they look. They have all these wonderful colors and they're the source of maple syrup. Is there concern that --
STERN: There's concern that this can spread, the way the plague of Japanese beetles did, which came over to this country maybe 50 years ago.
CURWOOD: Are some people saying you should just cut down all 200 of these trees that are infested and be done with these beetles?
STERN: There are about 4 potential strategies for dealing with this problem. One is insecticide, there's a chemical, a control called Foridan, either sprayed or injected into the tree. There's biological control. The woodpecker is a natural predator, he eats these beetles. But how are you going to get enough woodpeckers in the city streets? The other enemy of the beetle is entemo pathogenic nematodes, a very small unsegmented worm, but how do you get these nematodes to the scene. The third strategy is a trap tree. A trap tree is planted attracting beetles and drawing them away from the native population. In China this strategy is used to protect the poplar groves, and what they'll do is they'll plant the maple and let the beetles have it, thus protecting the poplars, and of course tree removal.
CURWOOD: Well, what could people do in their own back yards? I mean, if I have a maple tree and I want to protect it, what should I do?
STERN: We don't know. That's the problem because it's such a common-sense question. How, there's no vaccine as yet. It's very frustrating that you see this, and if you've been at the scene as I have, I've been to Greenpoint and saw trees that have been devastated by these beetles. And you see it start, you see it spread, like a plague. And you haven't yet worked out a solution and don't know if you can. It's sort of an Andromeda Strain applied to maple trees, and it's caused a great deal of concern.
CURWOOD: Henry Stern is New York City's Parks Commissioner. He spoke to us from member station WNYC.
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